In this paper, via the limit technique of long wave, the N-order rational solution of the (2+1)-dimensional B-type Kadomtsev–Petviashvili (BKP) equation is derived from the N-soliton solution. In particular, the bright–dark M-lump solution can be obtained from resulting N-order rational solution. This kind of lump wave in BKP equation exhibits the one-peak-one-valley structure which is different from that in KPI equation. In addition, graphical illustration presents the collision dynamics of multi-bright–dark lump waves.