Compositing with starch is an effective way to lower the cost of the poly (lactic acid)(PLA)-based biodegradable materials, while the compatibility of these two phases needs to be enhanced. Here reports an improvement based on vacuum heating treatment(VHT), hence a solid-phase esterification between PLA and crosslinked starch（CST） is enhanced. This research also studied the impact by esterified catalysts and starch proportion on thermal stability, surface morphology and mechanical properties of the composite. The result indicated that VHT shows positive effect on all aspects. Especially, sample with 20% CST shows optimized tensile strength of 62.6 MPa, and elongation at break was as high as 69.8%.