We select the oolitic outcrops of the Lower Triassic Feixianguan Formation in Dabashan fault zone to explore the compaction calculation of carbonate rock. Through the observation of oolitic morphology in the sample, it is considered that the discoid shape of the oolitic is formed by compaction(compressive stress), that is, the discoid form of the ooid can be used as the most intuitive and reliable basis for compaction. Based on the identification of heterogeneous ooid of different genesis, the method of calculating the compaction quantity by using the crushed ooid is put forward, and the compaction amount is obtained by measuring the amount of oolitic deformation. Considering that the compaction before the start of the oolitic deformation is difficult to estimate, this calculation is actually the minimum compaction of oolitic limestone in the sample, up to 41.7,. This method provides a useful idea.