Abstarct: According to previous studies on the positive effect of salicylic acid and biochar on mitigation of adverse effects of drought as well as improving water relations in the plant, therefore this study aimed to investigate the effects of biochar and salicylic acid (SA) on some characteristics of Borage officinalis L under different irrigation intervals. These experiments were performed in a four replicated-split plot factorial arranged in CRBD with three factors irrigation intervals (5, 10, and 15 days) in the main plots and biochar application (0, 5 and 10 tons per hector) and foliar application of salicylic acid (0, 0.5 Mm) in subplots. This study was carried out in the research field of Shahrood University of Technology, Shahrood, Iran during 2017-2018. The analysis of variance indicates that irrigation intervals × biochar had significant effects on leaf relative water content (RWC), the content of leaf flavonoid (FLV), chlorophyll b (Chlb), the number of flower shoots, the number of main shoots, the content of plant nitrogen (in the first year) and also ammonium (NH4), nitrate (NO3), nitrogen) of soil (in the second year) and soil respiration (RESP) (in the second year). Irrigation intervals × salicylic acid was significantly influenced RWC and FLV (in first and second year) and carotenoid (CAR), the weight of flower shots and total dry weight (DWT) (in the first year) and the content of fatty acid in seeds, the number of flower shoots, and the number of main shoots (in the second year). Biochar and SA interactions (Biochar × SA) was significant effects on the number of flower shoots, the number of main shoots and plant height (in the second year), DWT ( in the first year), organic carbon soil (C), membrane stability index (MSI), the content of leaf anthocyanin (ANTO), proline content (PRO) and different enzymes such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and shoot (SW) and leaf weight (LW) ( in the first and the second year) and Chlb and DWT, oilseeds (in the second year), and the number of flower shoots, plant height (in the first year). The results indicate that increasing irrigation intervals to 15 days declined significantly Chlb, Chl total, CAR, MSI, RWC, and total leaf carbohydrate. Also observed the positive effect of salicylic acid and biochar on some studied traits under water deficit. Biochar application increased CAR in the first year so that its amount increased by 43% and 73% at 5 and 10 tons per hector respectively. The application of biochar had a significant effect on increasing the dry weight of flowers, but no difference was observed between the values of biochar (5 and 10 tons per hectare) in this regard. The addition of biochar in both years caused a significant reduction of soil NO3 in all irrigation intervals compared to normal irrigation. The amount of antioxidant enzymes CAT, POD, SOD as well as the amount of proline amino acid in both cropping years increased at 10 day irrigation compared to the control which decreased sharply with reaching 15 days irrigation. Concomitant application biochar and SA improved the levels of the above enzymes compared to no application conditions. Increasing the above enzymes in turn were effective in reducing the adverse effects of water deficit condition by reactive oxygen free radicals. Also, by increasing the irrigation intervals, the percentage of seed oil decreased. Concomitant application of SA and biochar (10 tons per hectare) in 15day irrigation intervals caused a significant increase in oilseeds. The results of this study indicate the beneficial effect of biochar and salicylic acid (alone or in combination with biochar) on some plant traits and soil under borage cultivation in conditions of water deficit.