Let BH,K = {BH,K(t),t ∈ R+N} be an(N,d)-bifractional Brownian sheet with Hurst indices H =(H1,…,HN)∈(0,1)N and K =(K1,…,KN)∈(0,1]N．The properties of the polar sets of BH,K are discussed．The sufficient conditions and necessary conditions for a compact set to be polar for BH,K are proved．The infimum of Hausdorff dimensions of its non-polar sets are obtained by means of constructing a Cantor-type set to connect its Hausdorff dimension and capacity