Abstract: Rice straw was treated with Agaricus blazei and Valvariella volvac in different periods.The in sacco degradation experiment was carried out to study the effect of pre-culture on improving straw degradation quality.The results showed that comparing with V.volvac treated and untreated groups, the DM degradability of A.blazei treated straw increased by about 15.17%(PPV.volvac treated group, the Heel and Cel contents in residue decreased by 8.03% (PPA.blazei was euhured, the higher degradability was obtained.Dynamic of ruminal degradation revealed that the soluble proportion (a) and degradable proportion (b) of A.blazei treatment increased by 12.4%and 16.8%respectively, and its degradation (c) improved by about 0.0152.On the contrary, V.volvac treatment indicated no significant improvement in straw ruminal degradation quality (P>0.05).