A method for designing optimized polarization independent and temperature insensitive optical waveguide couples using fluorinated polyimide is presented. Based on measured polarization, temperature and dispersion characteristics of fluorinated polyimide, a 3 dB waveguide coupler with 120 nm bandwidth with minimal polarization and temperature variance is designed and verified through simulation based on three dimensional beam propagation. The coupling ratio of the theoretical device is (50±0.8)% for two orthogonal polarization modes in the waveband 1490～1610 nm and the temperature range -10～40 ℃.