If the elasticity of the top band of your thigh socks is insufficient or the size of the thigh socks is a little larger, these socks will slip easily. The best way is to match the garter belt, which can stabilize the thigh high socks. But it is not easy to finding a good garter belt, so if you can also try some simple methods.
Folding the Band inward will make the thigh high socks tighter. Folding the band inward once or twice is very helpful to help keep the thigh socks. This is the easiest and most convenient way. Doing so may cause some reduction in the height of the socks, but in most cases it is acceptable.
Wear two pairs of thigh high socks at the same time and keep the socks at the right height. The friction between socks and socks is much greater than between socks and skin. So if you cover loose thigh socks on the outermost side, they may be suitable. It might be a little hot, but it’s fun to wear it once in a while.
Also please don't try some wrong practices. In order to prevent the socks from sliding down, some girls use body gel on the inner thighs. This is not a good practice. Many body gels can damage the skin, make the skin itchy, and even ulcerate. Washing socks to make the socks shrink and shrink is also ineffective, because you cannot improve their elasticity. They will shrink as a whole, but there is still not enough elasticity to help thigh high socks stay on the thighs.