Abstract: Small rectangular Mao bamboo pieces were incubated after natural inoculation and artificial inoculation separately under different temperatures and relative humidities (RH) to test the effects of main environmental factors on bamboo timber moulding. The results from the multiple contrasts of the tests showed that under temperatures of 26℃ to 32℃, most sorious moulding of Mao bamboo timber occurred at 100% RH; the extent of moulding was positively correlated to RH; the moulding extent of Mao bamboo ripped timber exposed in July, February and January was significantly lower than that exposed in other months of the year.The two laboratory inoculation methods are recommended for the first time for rapid testing of the natural resistance of bamboo timber to moulds and evaluation of mould control treatments of bamboos. Also a primary standard for grading the extent of bamboo timber moulding was put forward for current use.Suggestions were made to store bamboo timber in a warehouse of special structure, with high base pillars under the floor and large windows; to put the bamboo timber and handcrafts in cross-ways in order to maximize air circulation and decrease the humidity at the surface of bamboo goods and choose suitable processing season to reduce mould damage.