A series of boron modified V-MCM-41 catalysts were in situ synthesized. The modification effect of boron to the vanadium species and catalytic performances were systematically studied. The catalysts could still maintain mesoporous structure and relatively large specific surface area after boron modification. Boron species were mainly in the form of triangular [BO3](3-) units on the surface and the pores of the catalysts. The introduction of boron could effectively enhance the dispersion of vanadium species and increase the amount of surface vanadium sites. The catalysts showed high activity towards iso-butane dehydrogenation. The results of catalytic tests showed that both the iso-butane conversion and iso-butane selectivity improved with the presence of boron species. The best catalytic performance was obtained on the sample with the maximum vanadium sites. The performance of the catalyst still remained stable after several cycles of tests and regenerations, which was promising for industrial application in moving bed or fluidized bed reactor in the future.