The Lower Paleozoic carbonate source rocks are thick and wide-distributed in Xiangzhong Depression so it is one of potential prospecting areas in southern China. Result of outcrop observation and sample analysis show that the source rocks mainly consist of argillaceous limestone, marl and limestone with high values of TOC and Ro. Organic matter is mainly Type-Ⅰ kerogen. Analysis of thermal evaluation of the source rocks demonstrate a model of hydrocarbon generation as following four stages: asphalt disaggregation(immature-low mature stage), kerogen degradation(mature stage), organic inclusion release(high mature) and thermal prolysis gas(overmaturate stage).