The invention provides a brake, a braking system and a vehicle. The brake comprises a brake cavity, pistons, a first channel, elastic components and brake components, wherein piston cavities are formed in the brake cavity; the pistons extend into the piston cavities, and can move relative to the piston cavities in a first direction and a second direction; the first channel communicates with the piston cavities, and liquid flows into the piston cavities via the first channel, and the pistons are driven by hydraulic pressure to move in the first direction; the elastic components are propped against the pistons; the pistons move in the first direction to compress the elastic components, and the elastic components recover elasticity and drive the pistons to move in the second direction; the brake components are connected with the pistons; the pistons move in the first direction to drive the brake components to get close to a brake disc; the pistons move in the second direction to drive thebrake components to get away from the brake disc. According to the brake provided by the scheme, the pistons can move bidirectionally by the elastic components and hydraulic drive, the brake components and the brake disc are completely separated during travel of the vehicle, and braking reliability and safety of the brake are improved.