An electrical connector 100 includes an insulative housing 1, a plurality of contacts 2 retained in the insulative housing 1 and a spacer 3 mounted in the insulative housing 1. The contacts 2 include a plurality of first contacts 210 each having a first extending portion 213 extending downwardly and a plurality of second contacts 220 each having a second extending portion 223 extending downwardly. The first extending portions 213 and the second extending portions 223 form two rows, respectively. The spacer 3 includes a base 31 and a lump 33 extending upwardly from the base 31. The lump 33 separates the first extending portions 213 from the second extending portions 223 along a front-to-rear direction to improve signal transmission quality of the electrical connector 100.