The preparation of bio-oil from different models of sick and dead pigs with microwave-conventional two-step hydrothermal treatment and its related characteristics were studied to realize the high-value transformation of multi-target products of sick and dead livestock and poultry. The results showed that the bio-oil yield of the experiment group showed a trend of first increasing and then decreasing with the increase of the conventional hydrothermal temperature of the terminal when the ratio of protein（P）， lipid（L） and carbohydrate（C） was 5∶20∶1 and 20∶5∶1. When P∶L∶C was 12∶12∶1， the bio-oil yield of the experiment group continued to increase with the increase of conventional hydrothermal temperature of the terminal. In general， the higher heating value （HHV） of bio-oil in model pigs with higher lipid content was relatively higher under the same reaction conditions. The interaction of the three components on the HHV of bio-oil was related not only to the proportion of components but also to the reaction temperature. The total-nitrogen （TN） conversion rate of bio-oils of the three models of sick and dead pigs reached the maximum value at 260 ℃， and that of aqueous phase products reached the maximum value at 280 ℃. It was feasible to regulate the migration of N element to improve the quality of bio-oil. The bio-oil prepared only by microwave hydrothermal treatment in the experiment group with P∶L∶C of 5∶20∶1 had the largest comprehensive combustion characteristic index of 8.22×10^-7 K^-3/min. It is indicated that the increase of lipid content can improve the comprehensive combustion performance of hydrothermal bio-oil from sick and dead pigs.