A microdevice structure of microchannel chip is provided which includes one gas channel and at least one liquid channel. The microchannel connects the gas channel and each liquid channel. The most basic microdevice of the mirochannel chip comprises micropressure sensor, microvalve, micropiston and micropump which are controlled by digital pressure gas microcircuit in the chip. Each microdevice isolates the gas phase and liquid phase by microhole without any movable component and any special ventilate or elastic material. The gas-liquid interface is driven by the pressure difference of gas phase and liquid phase to enable the microdevice to implement the functions, such as sensing pressure, switching fluid channel, transporting liquid effectively, and so on. All kinds of microdevices can be shaped on the hard material (for example glass) by etching, so as to integrate a great lot microdevices with low cost, and the structure of chip and these several microdevices can be formed by adopting other methods on other material.