Abstract: The paper aims to provide a theoretical basis for the growth regulation of pea in arid area by exploring the effects of drought stress and nitrogen forms on root growth of pea. Pot experiment was adopted to study the effects of 2 nitrogen forms and drought stress of 55% relative water content for 15 days on root growth of pea during different periods. The results showed that: the effects of nitrogen on root growth varied with nitrogen forms , and NO3--N promoted root elongation under normal water condition, while NH4+-N improved root diameter under normal and water stress condition; in addition, the influence of drought stress on root growth also varied with nitrogen forms, and the root length and volume as well as surface area under 3 drought stress forms during stress period and flowering stage significantly decreased under NO3-- N condition; furthermore, drought stress was beneficial to reducing root decay rate during maturity stage, which epitomized equivalent-compensation or over-compensatory effects on root growth. In conclusion, NO3--N was beneficial to promoting root growth and the compensatory effect of rewatering after drought stress during bud stage on root growth during maturity period was the best.