The critical currents of Nb3Sn practical superconductors were measured in high magnetic fields up to 22 T at 4.2 K. The conductors investigated were MF Nb3Sn wire, CVD-Nb3Sn tape and diffusion processed Nb3Sn tape. The measurements show that the conductors have excellent superconducting properties. The multifilamentary Nb3Sn wire possesses a higher overall current density Jcov(Nb3Sn + bronze), especially in high fields above 12T. Its Jcov, for example, is 2.4 × 104A/cm2at 15T. The CVD-Nb3Sn tape displays a higher Jc in the fields up to 12T, while the diffusion processed Nb3Sn tape has an excellent Jc(Nb3Sn) in high field. Their Jc(Nb3Sn) ,for instance, are 4.0 × 105A/cm2(at 11T) for CVD-Nb3Sn and 1.7 × 105A/cm2(at 15T) for diffusion processed Nb3Sn tape, respectively. The upper critical field Bc2 are determined extrapolately by using Kramer's scaling law for flux pinning. A discussion is presented respect of the results of measurement and the upper critical field.