The experiment experiment was carried out in two factors completely randomized experimental design with four replications. The first factor included two rice varieties (Hananomai và Kinu) and second factor included four combined concentrations of CaO and SiO2 (0; 0,4 g/l CaO+0,1 g/l SiO2, 0,8 g/l CaO+0,2 g/l SiO2, 2 g/l CaO+0,5 g/l SiO2). Results showed that spraying CaO combined with SiO2 did not reduce rice height. However, the combined concentration of 0,8 g/l CaO+0,2 g/l SiO2 increased number of shoots, hardness of ricestem, and rice yield significantly.