The L-shell X-ray emissions of tungsten has been investigated under the bombardment of C ⁶⁺ions in the high energy region of 154 - 424 MeV/u. Compared to the atomic data, the energy of the X-ray is enlarged, and the relative intensity ratios of Lı, Lβ _{1, 3, 4}and Lβ _{2, 15}to Lα _{1, 2}X-rays are enhanced. The L-subshell and the total X-ray production cross sections were calculated by a well corrected thick target formula and compared with the theoretical estimation of BEA, PWBA and ECPSSR. On the whole, the experimental cross sections are all smaller than the prediction of PWBA and ECPSSR, but in agreement roughly with that of BEA. It is indicated that the inner-shell ionization of W can be considered to be a binary process between the high energy C ⁶⁺ions acting as a point charge and the independent target electrons. With the L-shell ionization, the outer-shells are multiply ionized. The multi-ionization degree is regard to be almost constant in the present work. This results in the X-ray energy blue shift and the enhancement of the relative intensity ratios of Lı and Lβ to Lα X-ray. Using the atomic parameters corrected by multi-ionization, the X-ray production cross section can be estimated by the BEA model.