The invention discloses a narrow body car frame which relates to the field of car manufacturing technology, and comprises a reinforcing plate connected with a left longitudinal beam and a right longitudinal beam, the left longitudinal beam and a right longitudinal beam are divided into a front segment, a transitional segment and a rear segment; the front segment is provided with a first cross beam and a second cross beam, the rear segment is provided with a transmission shaft cross beam, a rear suspension frame front support cross beam and a rear suspension frame rear support cross beam as well as a rear cross beam. An outer side distance between a left longitudinal beam and a right longitudinal beam in the front segment is D which is equal to 860 millimeters; the outer side distance between a left longitudinal beam and a right longitudinal beam in the rear segment is d which is equal to 800 millimeters; the front segment is connected in front of the transitional segment, the rear segment is connected behind the transitional segment, the length of the transitional segment is L which is equal to 369 millimeters, a bending angle is Alpha which is equal to 4.7 degrees. The frame can solves the problems that the narrow body car frame has insufficient torsional resistance and rigidity, and the installation of an engine and a water tank is difficult.