As a new type of high-frequency band resource, terahertz wave has a higher carrier frequency, it can withstand larger bandwidth and transmission rate, therefore, it has become a research hotspot for new generation broadband communications. A 300 GHz terahertz wireless communication system is constructed based on pure electronic devices, in which the transmitter has a simple structure and the whole system is less complex than the photon-assisted system. Signal transmission experiments with wireless distances of 50 m and 100 m are conducted. The transmission performance of the system is explored and the relationships among the transmission performance, transmission rate and transmitting voltage are studied. As far as we know, 100 m is the longest distance that an all-electronic terahertz wireless transmission system can achieve without using a Power Amplifier(PA).