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A relatively wide bandgap and intrinsically phase instability of α-CsPbI3perovskites (PVSKs) greatly hinder their potential applications in solar cells. One of the popular solutions is based on high-concentration doping, which however encounters big difficulty in the balance between phase stability and optical performance. Here, we report the advance on bandgap alignment of CsPbI3through B-site (Pb2+cation) minor doping engineering employing density functional theory (DFT). It is discovered that the bandgaps could be finely aligned by minor doping of Si2+, Sn2+and Ge2+, which is caused by the downshift of conduction band minimum contributed by B-porbital level within CsPb1-xBxI3PVSKs, and thus offer shrunken gaps and enlarged imaginary part of dielectric function for enhanced photo absorption. Furthermore, the minor doping of Sn2+could not only bring a suitable tolerance factor for CsPbI3with a slighter lattice distortion, but also increase the charge density of Pb2+to enhance the interaction between Pb2+and I−, which consequently improve their structure stability.