Abstract: The mudflat soft clay with high soil moisture and low compression modulus should be enhanced before the practical foundation construction of offshore wind farm. To investigate the stabilized mechanism and micro behavior of mudflat soft clay solidified by the magnesia oxysulfate cement,the X-ray diffraction（XRD）tests were conducted to determine the micro-ingredients of the mudflat soft clay solidified by the magnesia oxysulfate cement composite curing agent. A series of scanning electron microscope（SEM）tests were conducted on the solidified soil with different soil moistures（w）,curing agent dosages（W_g）and ages（T）. Then,the effects of w and W_gand T on the micro-void,micro-morphology and the contact area ratio( R_CA)of the solidified soil were investigated by using Image Processing. It was found that the solidified soil was mainly constitutive of quartz,5·1·7 phase,dolomite,pyrophyllite,MF-A-S phase and a little of CaO and MgO. The stabilization of solidified soil is mainly due to the hydration and hydrolysis reaction of the modified magnesia cement,ion exchange and filling effect and the carbonation. The solidified soil mainly covers three types of microvoid:gelling and contact and skeleton,and it also contain three types of solid particles:foliated,granulous and clotted. The smaller the initial soil moisture,the larger the amount of curing agent and the longer the age,the greater the R_CA and the macro-physical parameters（initial tangent modulus, E_i,and shear strength parameters, c and φ）of the solidified soil. Finally,the functional relationships between E_i,c,φ and RCAwere established.