The testing method for detecting cement paste agglomeration is investigated. Furthermore, the procedure and feasibility are also discussed. Paste agglomeration is an abnormal phenomenon of part hydration along with many granules forming. Base on measurement of cement setting time, needle-penetration method is used to check the degree of agglomeration by vicat apparatus. Through researching the influence of cement fineness, content of gypsum and hydrating time on amount of agglomeration, the dependability, reproducibility and enantiotropy of this method are analyzed. The results show that the variation laws of paste agglomeration could be reflected by needle-penetration method effectively, and this method is easy to be carried out. There are better reproducibility and enantiotropy, and this method be used to study the mechanism of agglomeration.