The invention discloses alkali-containing borosilicate glass and a preparation method thereof. According to the preparation method of the alkali-containing borosilicate glass, the ratios of various glass components are controlled, the particle size of glass raw materials is controlled, the particle size of a silicon source material led-in SiO2 is smaller than 120 micrometers, and the particle size of an aluminum source material led-in Al2O3 is 20-100 micrometers. The ratio of an alkali metal oxide and an alkaline earth metal oxide in the glass components is controlled, so that the glass has excellent melting performance, and chemical stability, heat resistance and crystallization properties of the glass are improved. The distribution ratio of particle size of the silicon source material and the aluminum source material is controlled, content difference surface network formers and inner network formers of the glass is reduced, and the quality of the glass is improved.