For reservoirs with high mud content and low permeability，shrinkage swelling agent can reduce pressure and increase injection，but there are no research reports on the relevant mechanisms. In order to solve this problem，the influence of the dosage of shrinkage swelling agent（DSJ-1）containing quaternary ammonium and primary amine groups on the anti swelling rate and shrinkage swelling rate of bentonite was investigated. Then the bentonite before and after treatment was characterized by X-raydiffraction（XRD），X-ray fluorescence spectrum（XRF），Zeta potential，thermogravimetry，particle size distribution and optical microscope. The anti swelling and shrinkage swelling mechanism of DSJ-1 was analyzed. The results showed that during the anti swelling treatment process，DSJ-1 was mainly adsorbed on the surface of bentonite. The adsorption amount and Zeta potential had the greatest impact on the anti swelling rate. During the shrinkage swelling treatment，DSJ-1 was mainly adsorbed between crystal layers. The particle aggregate size and Zeta potential affected the shrinkage swelling rate.