In this paper, the Oil leakage sensor utilized photonics crystal fiber interferometer (PCFI) is proposed and experimentally investigated. The principle of operation of this sensor is detected the gas emission from pipe. This sensor is operate in transmission mode which designed by splicing the LAM-10 PCF with single mode fiber (SM) with two side. To increase the sensitivity of this sensor the splice region is coated by special polymer doping by nano sliver silver particles to increase the sensitivity. The experimental result s shows the sensitivity of fabricated sensor is high, and the response time is very short reach to 2min the max sensitivity is equal to (62 Co./sec ). Due to the low fiber loss, the sensing range can be as high as 1 km.