Flux pinning mechanism in superconducting NbTi composites with Ti5wt%Nb artificial pinning center is analyzed in detail. The results show that Fp(B) mainly depends on normal metal pinning mechanism and Dk pinning mechanism. The results suggeste that both normal metal pinning mechanism and Dk pinning mechanism are very important. The value of Fp(B) in lower magnetic field is mainly dominated by normal metal pinning mechanism and the value of Fp(B) in higher magnetic field is mainly dominated by Dk pinning mechanism. The function value of Fp(B) dependant on normal metal pinning mechanism and Dk pinning mechanism increase respectively with the decrease of the wire diameter.