In order to improve the integrity of the existing optical fiber digital measurement system

the corona losses monitoring system of bundle conductors using UHV corona cage based on optical fiber transmission is developed.The system consists of remote optical-fiber-transmission acquisition module

local merging module.The optical fiber is used to transmit data between remote module and local module

accurate and synchronous collection of voltage and current signals is realized by optical-pulse triggering.The PC software is designed by Lab VIEW

and the communication between local module and PC adopts the UDP communication protocol.The error testing results of the system by use of signal generator in laboratory show that angle error is within 0.009′and the ratio error is less than 0.03%.The system has been applied in measuring of corona losses of bundled conductors in the Ping’an county

and the corona losses under dry

moderate and heavy rainy conditions（with the rainfall ratio of 6 mm/h and 12 mm/h）and wet conductors are 67 gained.It’s concluded that this system can be set up further study on UHV AC bundle conductors’ corona losses law under different weather conditions in high altitude area.