The invention discloses pyrido[1,2-a]pyrimidone derivatives as a PI3K suppressor; and in particular, this invention relates to a compound of formula (I) or its pharmaceutically acceptable salts.本發明揭示一種作為PI3K抑制劑的吡啶并[1,2-a]嘧啶酮類似物,具體地,本發明係關於式(I)所示化合物或其藥學上可接受的鹽。