In order to investigate the effect of green manure and nitrogen levels on biomass production and nitrogen use efficiency in experimental purslane during two crop years of 1394-94 and 2014-95 at Birjand University Research Farm, a split plot design based on randomized complete block design with three replications. Four green manure including: control (no green manure), flower vetch (Vicia villosa L.), mandab (Eruca sativa L.) and mix of mandib and flower vetch as main factor and three levels of pure nitrogen fertilizer including: zero (control) , 50 and 100 kg ha-1 were as sub-factors. The traits studied in this experiment included: fresh and dry stem weight, fresh and dry leaf weight, fresh and dry weight of shoots, leaf to stem ratio, biomass nitrogen content, biomass nitrogen content, uptake efficiency, biomass physiological efficiency and biomass agronomic efficiency. They were. The results showed that application of clover and vetch blend in all treatments increased all the studied traits. Also, increasing nitrogen fertilizer increased shoot fresh and dry weight, shoot fresh and dry weight, biomass nitrogen content, uptake efficiency and biomass agronomic efficiency. The interaction of green manure and nitrogen on shoot fresh weight, shoot dry weight, percentage and nitrogen content of biomass, physiological and agronomic efficiency of purslane were significant. So that the application of green manure with 100 kg of pure nitrogen increased all mentioned traits. According to the results of this experiment, application of green manure, especially blend of vetch and vetch with 100 kg of pure nitrogen, increased biomass production and efficiency of purslane nitrogen application in Birjand region.