Firms self-select into exports according to their productivity due to the existence of export costs. Export performances of firms with weaker credit constraints are better relative to those with stronger ones. This paper shows empirically that credit constraints hamper firms, exports more for those with stronger credit constraints using Firm Survey Data from the Word Bank, within which loan of circulating capital from bank and that of fixed capital investment have unsymmetric influences. Loan of circulating capital has significant effects on both intensive margin and extensive margin, while loan of fixed capital investment takes effect on only extensive margin.