Human body communication（HBC）

which uses the human body itself as the propagation medium

has advantages of low power consumption

high rate and high security.It is regarded as an ideal communication method for body sensor network.A channel testing system of HBC is designed

which has character of floating ground and behaved like the real HBC scenarios.ARM7TDMI based Samsung S3C44B0X chip is adopted as development platform.In the transmitter end

the direct digital synthesizer（DDS） chip AD9910 is used to design adjustable frequency signal generator

and the logarithmic amplifier chip AD8310 is performed to realize the signal strength indicator in the received end.The output signal frequency range of the proposed adjustable frequency signal generator is 0 ～ 200 MHz

and the narrow-band spurious free dynamic range is larger than 80dB

the minimum resolution of the signal strength indicator is up to 0.1 dB.The system is battery-powered.A large amount of measuremental experiments are conducted successfully in the shield chamber to investigate the human body characteristics by using this system.