Abstract: A retaining device for a heat-dissipating apparatus includes a first and second members, a retaining module and four retaining elements. The first member has at least one positioned slot formed at two ends thereof, a through hole formed at a centre thereof, and at least one locking pin adjacent to the through hole. The second member has at least one positioned slot formed at two ends thereof, a through hole formed at a centre thereof and at least one first fixing and second fixing holes formed around the through hole. The locking pin wedges in the first fixing hole. The retaining module is inserted in the through holes of the first and second members for fixing. The four retaining elements insert in the positioned slots of the first and the second members. The present invention can be adjustable in configuration and scale to fit for different mounting holes.