A high-precision three-component electromagnetic field sensor and a data transmission control system therefor. The high-precision three-component electromagnetic field sensor comprises a box body (1), wherein an X-direction coil structure (2), a Y-direction coil structure (3) and a Z-direction coil structure (4) which have the same structure are arranged in the box body (1); normal directions of the X-direction coil structure (2), the Y-direction coil structure (3) and the Z-direction coil structure (4) are orthogonally combined; a gradienter (5) is arranged in the box body (1); and a circuit control board and a battery (6) are arranged in the box body (1). The exploration explanation precision of an electromagnetic method is improved; potential safety hazards of hidden geological disasters are reduced; an ARM and FPGA combined control mode is used, an FPGA performs real-time collection, and an ARM performs subsequent processing, storage and transmission, such that the overall use performance of a system is effectively improved; and a GPS time service device can make each sampling point have an accurate timestamp, and the deviation between same and an absolute time is less than 30 nS, thereby ensuring the accuracy of data transmission.