In order to find optimal pretreated wheat straw utilization on soil improvement, soil samples were collected from indoor incubation experiment of different wheat straw utilizations, seven separate indicators, including 150min of cumulative infiltration (I150), available soil water content (θ), cumulative evaporation (Ec), soil aggregate fractal dimension (FD), soil pore fractal dimension (Dp), straw decomposition rate (Rd) and total nitrogen (wTN), were chosen to evaluate the effect of different pretreated wheat straw utilizations on soil improvement (e.g., water infiltration capacity, soil moisture availability, waterholding capacity, structural stability, soil porosity, straw decomposition rate and soil total nitrogen content). The principle component analysis method was used to conduct the above mentioned seven indicators, then comprehensive improvement index of soil improvement of wheat straw utilization was established by weighted sum of different evaluation indices. Result showed that comprehensive improvement quality principle component obeyed normal distribution significantly and had good representation and objectivity, which could include 86.93% primordial quality attribute variation information, so it could be used as the overall pretreated wheat straw utilization improvement evaluation index of the seven indicators, wTN,Dp, FD and θ contributed the largest percentage (49.92%) in the first common factor, while Rd, I150 and Ec contributed the most (37.01%) in the second common factor. The treatments order of wheat straw utilization improvement was T6>T7>T3>T5>T4>T2>T1. Comprehensive soil amendment of ammoniated straw was better than that of non-ammoniated straw, comprehensive soil amendment of pulverized straw was better than that of non-pulverized straw, ammoniated straw mixed with calcium sulphate improver was better than that of mixed with aluminum sulfate improver.