Temperature logging curves at 8 boreholes and well-testing temperature data at 142 boreholes are used to determine geotemperature gradients in the Bohai Basin. The thermal conductivities of 86 rock samples are measured at laboratory and the effects of porosity and temperature are corrected to obtain conductivities in situ. Terrestrial heat flow densities at 76 wells are determined based on these data. The distribution of the heat flow indicates that the terrestrial heat flow in the Bohai Basin is relatively high with an average value of 65.8 mW/m2. This characteristic is caused by the tectonic evolution of the basin. During Cenozoic, the lithosphere stretched intermittently and the crust thinned so that heat conducted from the mantle increased and formed thermal abnormity at depth beneath the basin.