A high sensitivity near infrared fiber-optical power meter is designed on the basis of InGaAs photodiodes. Because the preamplifier circuit of this optical power meter is designed with a multilevel amplification range and a shielding box is added in, the measurement dynamic range is improved. In the power meter, the system common-mode noise is suppressed by a differential amplifier and a differential A/D conversion chip; the ambient temperature is measured by a temperature sensor; and the preamplifier circuit is adjusted to zero automatically by a D/A conversion chip. Thus, the stray light noise of the system, the dark current of the photoelectric detector and the temperature drift of the photoelectric detector are suppressed. The test results show that the light power measurement sensitivity of the fiber-optical power meter is up to -90 dBm in the fiber-optical communication band. Its measurement dynamic range, system signal-to-noise ratio and linearity are improved notably.