A high-solid two-stage process was proposed to increase biogas yield, to improve the efficiency and to stabilize the digestion process of horticultural waste (HW) and food waste (FW). In this two-stage process, high-solid codigestion of FW and chicken manure (CM) was carried out in the first stage and then, transferred and codigested with grass in the second stage. When volatile solid (VS) ratio of FW, CM and grass was 4:5:5, after 70 days, the cumulative methane yield was about 203 mL/g VS. The optimized operation parameter for the two-stage is VS ratio of FW/CM/grass as 4:5:5, duration of first stage as 3 days. Compared with the codigestion of FW, CM and grass, the biogas yield of the two-stage process increased by 28% and the duration of digestion was 52 days, 18 days shorter. Under the optimal condition, the VS removal exceeded 55%. The composition analysis revealed that cellulose and hemicellulose contributed to the production of biogas.