In this paper we present the structure and primary results of a stability monitor system

which is newly constructed for a macromolecule crystallography station (1W2B) of Beijing Synchrotron Radiation Facility (BSRF). The system consists of optimized double-blades beam position monitor (BPM)

double-wires BPM

fluorescence target

ion chamber

and fluorescence detector etc. It monitors the incident beam at front end and sample position and finds the source of beam instability immediately. Otherwise

by virtue of the system

the position of the electron orbit in insertion device can also be monitored in real time that gives an important advice of building slow feedback system of BSRF.