The Pt-195 and Sn-119 Knight shifts in U3Pt3Sn4 have been measured in the temperature range 4.2-298K. They exhibit Curie-Weiss like behaviors above about 50 K and remain constant below about 10 K. This suggests that the deviation of chi(T) from the modified Curie-Weiss law is an intrinsic property of U3Pt3Sn4.