A fixing structure of electronic components has a first substrate, at least one second substrate, at least one electronic component, and at least one fixing mechanism. Each second substrate has at least two first pins to electrically connect to the first substrate. Multiple second pins formed on a side surface of the electronic component are electrically connected to the second substrate. The at least one fixing mechanism covers the at least one electronic component and the at least one second substrate. A first mounting part and a second mounting part respectively extend downward from opposite sides of the at least one fixing mechanism for clamping the electronic component and the second substrate so that the at least one electronic component and the at least one second substrate are erectly mounted on the first substrate. Thus, more electronic components are allowed to be erectly mounted on the first substrate.