Abstracts: Based on the tests of fluidity of cement paste, the compatibility between a new type of lignified-poly aliphatic superplasticizer and cement is investigated and the tests is carried on with different contents of superplasticizer, different cement clinker and fineness and different types and contents of addotoves. The results show that the compatibility between lignified-poly aliphatic superplasticizer and different types of cement is good when the content of superplasticizer is 1.6%. When the specific surface area of cement is more than 4000cm2/g, the fluidity loss at 30min or 60min becomes greater by the increase of specific surface. When the content of C3A in clinker is lower (less than 10%), lowing the ratio of C3A/C2A could reduce the fluidity loss of cement paste. The compatibility between lignified-poly aliphatic superplasticizer and cement can also be improved when fly ash and slag are added with together.