Abstract: CF_3I is an important molecule in the field of infrared laser chemistry, but its rotational structure of vibrational bands remained unresolved so far because of its small rotational constants. The diode laser infrared spectroscopy of ν_4 band under the resolution of 0.002 cm~(-1) is reported here. About ten Q sub-braches, and some thousands of ~PP, ~RR lines were observed, two hot bands ν_4+ν_6←ν_6 and ν_4+ν_3←ν_3 were also investigated. Possible vibration-rotation interactions in ν_4 band were studied. Some of ~RR lines were assigned and least-squares fitted to get the molecular constants, some are improved and others are reported for the first time.