The present invention relates to a wheelchair brake assembly comprising a seat brake system and a wheel frame brake system. The seat brake system and the wheel frame brake system are separable from each other. The seat brake system comprises a caregiver brake lever and an actuating member, the caregiver brake lever being coupled to the actuating member. The wheel frame brake system comprises a brake transmission assembly, a first brake mechanism and a second brake mechanism which are adapted to be provided on a first wheel and a second wheel of the wheelchair respectively. The brake transmission assembly is coupled to the first brake mechanism and the second brake mechanism. The brake transmission assembly comprises an actuating lever having a first free end and a second end. The second end is coupled to the first brake mechanism and the second brake mechanism. The actuating lever is rotatable about an axis perpendicular to the longitudinal extension of the actuating lever and located between the first free end and the second end of the actuating lever, wherein the actuating member is adapted to operate on the first free end of the actuating lever to cause the actuating lever to rotate.