Soliton amplitude squeezed state is obtained and dctected by using asymmetric Sagnac interferometer and balanced homodyne detecting system.An improved photo detector circuit for quantum state detection is introduced.The circuit has a bandwidth of 10MHz and the saturation power is about 19 mW.A maximum photocurrent noise reduction of 1.1 dB below the shot noise is achieved.Taking the detection efficiency into account,the squeezing will be about 1.5 dB.