Abstarct: Atmospheric pressure non-equilibrium cold plasmas have received much attention in industry and medicine due to their high chemical reactivity and room temperature. Among the various types of plasma machines, atmospheric cold plasma jets have become very popular in medical and biological applications due to their unique properties. Atmospheric plasma jets, in addition to having the general advantages of cold atmospheric plasmas, are not limited to plasma production space for material processing and can process any type of body, regardless of its size and dimensions. The use of helium gas as the working gas of this system reduces the temperature in this type of plasma and makes it more desirable for processing heat sensitive surfaces. In order to use this plasma more and better, it is necessary to study the behaviors and the effect of its related parameters. In this dissertation, the behaviors of atmospheric plasma jets in the plasma laboratory of Shahroud University have been studied and its behaviors have been recorded during changes in electrical parameters, and factors such as discharge current, jet length and plasma power have been calculated. Also, by performing optical spectroscopy, the active species in the plasma jet in the upper, middle and downstream areas of the jet have been recorded and studied.