The work aims to study the effect of SiO2 content on the bioactivity of laser cladding gradient bioceramic coating on the titanium alloy. The coatings doped with different contents of SiO2 were fabricated on TC4 by laser cladding technology and design idea of gradient composition, with the fixed amount of rare earth oxide La2O3 in the coating. The effect of SiO2 content on the structure and bioactivity of laser cladding gradient coating was studied with OM, XRD, SEM, MTT and FDA. SiO2 could reduce the cracking sensitivity of the gradient bioceramic coating during the laser cladding and refine the grains. The coating with 2.5% SiO2 induced the most amount of HA+CaTiO3 during the laser cladding. The coating with 7.5% SiO2 demonstrated the strongest ability of mineralization and deposition in the simulated body fluid (SBF). The MTT test showed that the OD value of the proliferation number of cells in the coating with 7.5% SiO2 was the highest, and the cells could grow close to the coating surface. FDA staining analysis showed that the coating with 7.5% SiO2 had the largest number of cells and the cells were distributed evenly. The doping amount of SiO2 profoundly affects the amount of bioactive ceramic phase HA and Ca2SiO4, and further influences the bioactivity of bioceramic coating. The coating with 7.5% SiO2 possesses the best biocompatibility and bioactivity.