A fiber—embeded optical isolator with in-line fiber polarizer is proposed and fabricated. The optical isolator consists of the in-line fiber polarizers, the crystal Faraday roator, and the fiber GRIN—rod coupling system. In the coupling system, the both conventional and polarization maintaining single—mode fiber have been utilized. Isolation and insertion losses at I. 5pm are 25dB and 4. 5dB, respectively.