To screen the concentrations of targeted drugs， a cell co-culture microfluidic device with an integrated concentration gradient generator was designed and fabricated. The principles of concentration gradient generation， the concentration fields， the velocity fields， and the ability of cell co-culture within the device were studied. A microchannel model capable of generating a 5∶1∶0 concentration gradient was designed based on the equivalent circuit principle， using a series-parallel structure to integrate the concentration gradient unit with the cell co-culture unit. The velocity and concentration fields were simulated and validated using the laminar flow and mass transfer modules in the finite element simulation software Comsol. The microfluidic device was fabricated using soft lithography techniques， and fluorescein sodium solution and polystyrene suspension with a 1 µm diameter were used to simulate drug concentration distribution. Co-culture of Hela cells and A549 cells was performed within the device， and the growth curves and folate receptor targeting of both cell types were analyzed. Simulation and experimental results indicate that the designed microfluidic device could generate the desired concentration gradient （5∶1∶0 ratio）， with concentration variation within each branch cell culture unit below 0.1%. The velocity distribution in the cell culture unit is uniform， with an average flow velocity of （7.1±0.3）µm/s under an inlet flow rate of 925 µm/s. The growth of both cell types follows an S-shaped growth curve， and membrane staining experiments demonstrate the successful parallel co-culture of two cell types within the microfluidic device. These findings demonstrate that microfluidic device could simulate the in vivo fluidic environment of cells and provide a technological platform for targeted drug concentration screening and personalized therapy.