Abstract: A long chain hydrophobic modified styrene-acrylic copolymer emulsion was prepared with seed emulsion polymerization using styrene(St) and methyl methacrylate(MMA) as hard monomer, butyl acrylate(BA), acrylic acid(AA) and hydroxyethyl acrylate(HEA) as soft monomer, stearyl acrylate(SA) as functional monomer, potassium persulfate(KPS) as initiator, polyoxyethylene octyl phenol ether-10(OP-10) and sodium dodecyl sulfate (SDS) as compound emulsifier. the copolymer was characterized with ¹HNMR, SEM, TEM, TGA, etc. And its sand-fixation performance was studied. The results showed that when the mass ratio of emusifiers of SDS to OP-10 was 1 ∶ 1 and the hydrophilic lipophilic balance(HLB) was 27.50, the emulsion was the most stable with an average particle size of 1.423 μm and a TSI of 0.413. When the amount of stearyl acrylate(SA) was 3%(the total mass of monomer), the thermal decomposition temperature of polymer was about 340 ℃, the hardness of film reached to 3 H, the water absorption rate decreased to 3.25% and the water contact angle increased to 78.6°. The modified styrene-acrylic copolymer emulsion could be used as a sand solidification agent with a solid content of 15% and a dosage of 5 g/cm³, the unconfined compressive strength of the sand column was 118.32 kPa, the shear strength was 16.53 kPa, the internal friction angle was 8.68°, the relative resistance to erosion rate of the sand table was 98.2%, and the relative resistance to wind erosion rate was 100%.