Labile polymer microspheres were prepared by inverse emulsion polymerization by using acrylamide (AM), 2 - methyl - 2 - acrylic amide propyl sulfonic acid (AMPS) as monomers. Morphology of labile polymer microspheres is irregular spherical particles, microsphere size matches the micro/sub-micro size of pore throat. The structure of labile polymer microspheres were confirmed by Infrared spectroscopy. Secondary gelling results show that the gelling time extended with the increase of salinity and apparently shortened with the increase of temperature, Secondary crosslinker FQ has little effect on gelling time, but significantly affect gel strength. the gel with controllable gelling time（about 1 ~ 3 days）,good thermal stability and without dehydration can be obtained when the temperature > 90 ℃, degradable polymer microspheres with amount of 1.5% ~ 2% and the secondary crosslinker FQ with amount of 0.5% ~ 1.2%. In the oil phase, degradable polymer microspheres can’t conduct secondary crosslinking which indirectly prove its plugging selectivity . SEM experiment confirmed that the secondary gel process of degradable polymer microspheres, namely particles crosslinked to form particles aggregate, and then particle aggregats crosslinked to form large aggregate and the finally to form bulk gel.