A Spice sub-circuit macro model for annular gate LDMOS is presented. The macro model divided the annular gate LDMOS into two parts based on its structure. The middle part of annular gate LDMOS was a conventional LDMOS transistor whit rectangle gate. The terminal part was an annular gate LDMOS, and it was modeled individually. The macro model was verified by the N channel LDMOS in a 40 V BCD process. The results show that the macro model has good ability of geometry scaling and it can fit the characteristics curves of different size devices exactly. The macro model is compatible with commercial circuit simulator Hspice and Spectre.