A plug connector compatible to type-A USB 3.0 standard includes an insulative housing having a supporting portion, and a number of contacts divided into a first contact group and a second contact group on the insulative housing. The first contact group includes a number of first contacts compatible to USB 2.0 standard. The second contact group includes a number of second contacts compatible to USB 3.0 standard together with the first contacts. Each first contact and each second contact includes a flat first soldering section and a flat second soldering section, respectively. The flat first soldering sections and the flat second soldering sections are supported by and exposed on a single side of the supporting portion. As a result, cables can be easily and simultaneously soldered to the first and the second soldering sections for improving assembling efficiency.