Against the backdrop of accelerating urbanization, the contradiction between parking efficiency and land intensification has become prominent. In traditional circular stereo garages, a single elevator results in low scheduling efficiency, whereas two elevators lead to a 1.78-fold increase in floor space. Aiming at this contradiction, this research builds an intelligent IoT (Internet of Things) based on PLC (Programmable Logic Controller) technology, designs and implements a high-speed and small-area intelligent circular stereo garage system. By creating a "dual elevators—multiple turntables—collaborative pipeline" model, the system efficiency is increased to 1.4–1.8 times that of the traditional system. The design of "linear motor–variable length parking -extendable guide rail" innovates the shaftway reuse mechanism, reducing the land occupation by 13% than single-elevator, doubling the speed of pure elevators. An optimized strategy of "intelligent reservation, integrated scheduling, and dynamic path" is innovatively proposed, achieving intelligent management of the entire multi-task process. Data shows that the final vehicle throughput efficiency is increased to 1.7–2.7 times compared to traditional systems. This system architecture and collaborative system framework based on PLC-IoT provide an innovative model for efficient space and high-speed services in urban parking. It promots the intelligent transformation of stereo garages and having broad application prospects.