Abstarct: The application of new and non-destructive technologies for decreasing the negative effects of environmental stresses is one of solutions in agriculture as drought is one of the most important factors limiting grow, yield and changing some physiological and morphological characteristics of plants. A field experiment as factorial baxsed on randomized complete block design with three replications was conducted in research farm of Shahrood University to study this issue. Treatments consisted of three levels of drought stress including control (complete irrigation), no irrigation in the dough stage onwards, and no irrigation in the flowering stage onwards, exposure to ultrasonic waves with frequency of 42 kHz at five levels including control, 2, 4, 6 and 8 minutes. The results showed that drought stress at flowering stage reduced the dry weight of pods, plant height, stem diameter, number of nodes per shoot, leaf area, number of branches, number of 2nd order branches, distance of the first pod from the soil, pod length, seed weight, number of pods per square meter, number of seeds per plant, seed yield, biological yield, harvest index, but increased the remobilization of dry matter and protein content. the percentage of dry storage and transport of grain protein. The stress applied to the dough stage increased seed phosphorus and potassium. There was no statistically significant difference between drought stress at flowering and dough stage for harvest index, seed protein content. Irradiation of cowpea seeds with ultrasonic waves significantly increased leaf dry weight, stem dry weight, plant height, stem diameter, number of nodes per stem, number of branches, number of 2nd order branches, distance of first pod from soil, dry weight of pods, number of seeds per plant, seed yield, and the content of potassium, phosphorus, protein in seed. The interaction of ultrasonic waves and drought stress was significant on stem diameter, plant height, distance of first pod from soil, number of 2nd order branches, number of pods per square meter, number of seeds per plant and seed phosphorous. Except phosphorous, the irradiated plants grown in non stress conditions had higher values of these attributes