Disclosed is a brake caster with stroke adjustment mechanism, including a retainer, a king pin, a catch spring, a catch/release button, a plunger block, and a brake pad. The upper part of the king pin is fitted with the spring coil; the catch/release button is fitted with the catch spring; and a threaded polygonal lock nut is placed over the catch/release button in the hollow space of the plunger block, which has the brake pad installed on the bottom end; the plunger block being coupled with the catch/release button is slipped onto the king pin lengthwise along the threads. By twisting the plunger block in and out around the neck of the plunger block, the stroke distance can be adjusted according to different levels of rubber on the wheel, so that the service life of the caster can be effectively prolonged without numerous replacements of the wheels.