RBM15 is an RNA binding protein that is known of involving in the m⁶A modification and the regulation of alternative splicing (AS). However, how RBM15 regulates AS is currently unclear. Here, using super-resolution microscopy, we found that RBM15 forms puncta structures that closely contact with or even embedded in the nuclear speckles. Nuclear speckles are enriched in splicing factors, which implies that RMB15 might be involved in RNA AS. To determine whether and how RBM15 regulates AS, we knocked down RBM15(RBM15-KD) using siRNA and performed RNA-seq for wildtype(WT) cells and RBM15-KD cells. We analyzed the RNA-seq of WT and RBM15-KD cells. We show that RBM15-KD cause 1 279 differential AS events in 1 111 transcripts. After comparing to public RBM15-CLIP data, we identify that 191 out of 1 111 transcripts are directly bound by RMB15, indicating that these 191 transcripts are probably direct targets of RBM15. Moreover, RBM15 promotes the retention of the adjacent regions proximal to its binding sites in 121 out of the 191 transcripts. This study reveals that how RBM15 regulates AS on a transcriptomic level.