Nano-sized SnO₂ and bimetallic Pd-Cu/SnO₂  catalysts were successfully prepared via the thermal decomposition method and the impreganation method, respectively. Then, the nano-sized SnO₂ was characterized by means of XRD, TEM and specific surface area analyzer, etc. , and the catalytic reduction activity and selectivity of the nano-sized Pd-Cu/SnO₂  for nitrate nitrogen were analyzed at atmospheric pressure, with formic acid as the reducing agent. The results show that （ 1 ） the prepared nano-sized SnO₂ is of a crystalline size of about 8.9 10. 4 nm or 9.3- 10. 7 nm, with a particle size of about 10. 0 nm and a BET specific surface area being up to 144. 9892m² /g; and that, in the catalytic reduction of nitrate at a Pd-to-Cu ratio of 6：1 and a formic acid dosage of 16. 0mmol/L, nitrate is completely reduced; 76.23% of the total nitrogen is removed; the catalytic activity reaches 0. ll9mmoL/（min· g） ; and the optimal pH value is 4.0