Silicon-based channel waveguides are poled by thermal poling.A fiber-based(single mode) Mach-Zehnder interferometer is utilized to measure the linear electro-optic effect.Poling conditions(poling temperature,poling time,poling voltage) are optimized in air environment.The results show that,the electro-optic codfficient is(rTM=0.059±0.001 pm/V,rTE=0.053±0.001 pm/V) at the optimized conditions(406 ℃,20 min,-2.4 kV).At the same time,the waveguide has a lower threshold of poling voltage(100 V).The results also suggest that the electro-optic cofficient increases of 15% at negative poling than positive poling.