The invention discloses a ground signal sending device, a downhole signal receiving device and a data transmission system. The ground signal sending device arranged at the ground end comprises a ground controller, a ground transmitting circuit and a ground transmitting antenna, and a control instruction is processed through the ground controller and the ground transmitting circuit in sequence and then transmitted through the ground transmitting antenna. Compared with a common pulse remote control instruction transmission mode, starting and stopping of a pump are not needed, the drilling time is not delayed, wrong operation is not prone to generation, and reliability is higher. A data frame structure is more flexible and complex, more diverse control instructions can be sent (a traditional operation of starting and stopping the pump can only send several fixed instructions), in the drilling process, the work condition of an downhole execution mechanism can be optimized in real time, work of the downhole execution mechanism can be controlled, and great positive significance for safety and high efficiency of drilling is achieved. In addition, the ground signal sending device, the downhole signal receiving device and the data transmission system are simple in structure, high in reliability, easy to realize under the conditions of existing domestic technical level and machining technology and good in use effect as proved by on-site application.