The invention relates to a nuclear magnetic resonance detection device and a nuclear magnetic resonance detection method for the advanced detection of a water bodies in the front. In the device, a computer is connected with a system controller, a high-power power supply and a signal acquisition unit by a serial port bus respectively; and the system controller is formed by connecting a bridge circuit driver, a high-power H-shaped transmitting bridge circuit, a resonant capacitor and a transmitting coil. Compared with the prior art, the device can detect important information such as the existence of water-bearing bodies in the front, the water content of the water-bearing bodies and the like accurately and effectively. The occupied area of the coil is reduced effectively by a mode of arranging the coil vertically, so that the device can perform exploration in narrow space. The device can detect the underground geological condition within a certain distance in the front directly and accurately in production fields of coal fields and mines or construction sites of tunnels so as to reduce mine accidents caused by geological disasters such as water burst, mud gushing and the like due to unclear geological conditions in the front or various incidents caused by the geological disasters in the process of tunnel construction.