A method of making a contact module of an electrical connector which includes a front tongue and an upper and lower rows of contacts with contacting portions exposed to two opposite surfaces of the tongue is characterized by the steps of: forming a first insulator to the lower row of contacts to have a base, a lower upright portion, and a rear mounting portion; mounting the upper row of contacts to the first insulator by inserting tails of the upper row of contacts through the mounting portion of the first insulator until respective bearing portions of the upper row of contacts bear against the mounting portion; removing a carrier strip from the bearing portions of the upper row of contacts; and molding a second insulator with the upper and lower rows of contacts and the first insulator to expose the upper and lower contacting portions.