The photomultiplier-cell photomicrometer is an essential instrument in app- raising and analyzing mineral (especially for metal mineral). Up to the present, the best way to quantitate accurately various optical quality (including reflectivity, transmissivity, reflective transmission and apparent angle of rotation of heterogeneous substance, etc,)is the method of plzotomultiplier-cell. In 1978, adopted transistor circuit, the authors had assembled a complete mo- del of instrument connected with Orthaolux- Pol BIk microscope to constitute the photomultiplier-cell photomicsometer, which was made use of an illuminant vol- tage-stabilizer, direct current high-voltage stabilizex and photomultiplier-cell direct current operational amplifier. In 1981，a new design was found application. Inte;rated circuit and digital display had been put to use in the reformed instrument. So it is featured with less in measure limit (the inferior limit is 5 micron)，high precision (relative errox is measpre is below 2%)，little volum and easy to handle.