A toy vehicle, a toy assembly device and a related method includes a toy body having a plurality of component members, and a plurality of support frame members respectively supporting the component members. The component members and the support frame members have respective engaging portions that can engage and disengage in a horizontal direction. Each of the support frame members has a fitting part provided thereon for connecting the support frame members to one another. Each of the component members has a fitting portion provided thereon for connecting the components members to one another. When the support frame members, each with a component member supported thereon, are connected to one another through the fitting parts, the component members are connected to one another by the fitting portions to form the toy body, so that the toy body can engage with or disengage from the support frame members connected to one another.