The invention discloses a residue number systems (RNS) comparator, which comprises a first n-position phase inverter array, a modulus 2<n> adder, a second n-position phase inverter array, a modulus 2<n>-1 adder, a first n+1-position phase inverter array, a modulus 2<n>+1 adder, a third n-position phase inverter array, a second n+1-position phase inverter array, two input exclusive OR gates, a first carry save adder with end around carry, a second carry save adder with end around carry, a 2n-position binary adder, a first operational module, a second operational module, a first 1-position phase inverter, a second 1-position phase inverter and two input AND gates. According to the RNS comparator, subtraction operation is directly carried out in a residue number system, and an operation result in the residue number system is then converted to a binary system, so that the contrast process of the comparison is simplified, the resource consumption is reduced, and the operation speed is also improved.