Abstract: The soft-mold aided co-curing process for an advanced grid stiffened composite structure (AGS) is a complex multi-field coupling duration，which includes the temperature, cure degree and stress fields. The product quality of AGS depends on technical parameters determined by the curing environment. Based on the finite element method, a numerical simulation strategy of the co-curing process for an AGS is proposed. The influences of technology gap, curing environment and cure cycle on the distribution of coupling fields in the AGS prepreg are discussed and the determination method of co-curing technical parameters is presented. The present work would be valuable for the technical design of a soft mould aided co-curing process.