Abstract: Abstract :In order to Looking for a proper mother culture medium formula that made mycelium grow fast and strong , test was carried out in laboratory to study the effect of different wheat bran content as nitrogen source in mother culture medium on the mycelium of stropharia rugosoannulata farlow. The results showed that the ratio of nitrogen in mother culture medium affect the density, uniformity, growth potential, average growth rate of mycelium, and 15% and 20% wheat bran in mother culture medium were the best, and as nitrogen source wheat bran was better than peptone. the results also showed that stropharia rugosoannulata farlow mycelium growth trend is a “S “type curve , with wheat bran content of 15% and 20% in mother culture medium mycelium extended longer than others in the period of 12 to 24 days;mycelium stage growth rate trend was “fast→ slow→fast → slow”, In 0 to 3 days, 3-6 days, 9-12 days, 12 to 15 days, mycelium grew faster, in 6-9 days and 18 - 30 days grew relatively slow, and each stage in 0 – 18 days , growth rate were highest in condition of 20% wheat bran addition.