The present invention discloses an electrical connector and an electrical connector assembly. Each of the ground terminals is provided to be in contact with two corresponding first mating terminals in a left-right direction. The terminals may mate with the first and second mating terminals under the same specification, thus facilitating unified automatic production of the mating connector, and may achieve the objectives for increasing the shielding effect of the electrical connector and saving the quantity of the terminals without changing the size of the electrical connector.