Polyacrylamide　(PAM)　is　a　polymer　compound　that　is　widely　used　in　oil　extraction,　wastewater　treatment,　food　processing　and　other　fields.　As　a　typical　polymer　flooding　agent,　PAM　has　received　much　attention　in　the　field　of　oil　extraction　due　to　its　unique　of　viscoelastic　properties.　However,　polymer　flooding　faces　several　challenges　in　oil　reservoirs,　including　high　injection　pressure,　high　shear　loss　and　crossflow.　In　an　effort　to　overcome　this　challenge,　we　designed　a　method　of　coating　Ca2+　cross-linked　sodium　alginate　onto　the　core　structure　of　polyacrylamide,　providing　shear　resistance　and　sustained　release　performance　for　the　polymer.　The　important　role　of　the　shell　material　was　indirectly　demonstrated　by　measuring　its　apparent　viscosity　using　digital　rotary　viscometer.　Moreover,　the　swelling　behavior　of　microcapsules　in　water　was　observed　using　an　optical　microscope.　The　protective　shell　made　the　slow　release　of　anionic　PAM　into　water　under　stirring　at　500　rpm,　maintaining　the　viscosity　of　the　fluid　below　10　mPa　center　dot　s　within　2　h,　and　the　viscosity　increased　from　1.8　mPa　center　dot　s　to　30　mPa　center　dot　s　after　35　h.　In　addition,　this　work　revealed　the　importance　of　effective　encapsulation　by　emulsification/external　gelation　method　and　a　facile　shell　modification　by　the　layer-by-layer　self-assembly　method.　[GRAPHICS]