Objective To reduce aerodynamic noise in small axial fans blades with different perforation diameters were designed near the trailing edge. This study compares the prototype fan with perforated fans to investigate the effects of perforation diameter on aerodynamic performance and noise of fans. Methods The Reynolds-Averaged Navier-Stokes RANS method was used to simulate aerodynamic performance of both prototype and modified fans. On the basis of steady-state simulations Large Eddy Simulation LES coupled with the Ffowcs Williams-Hawkings FW-H acoustic equation was employed to simulate fan noise. Aerodynamic performance and noise tests were conducted on 3D-printed models to obtain performance parameters under different flow conditions. Results Perforating the blade can induce airflow on the blade surface improve blade surface pressure distribution delay boundary layer separation and suppress tip leakage vortex intensity. Under design conditions the perforated fan with 2. 5 mm diameter showed optimal performance static pressure increased by 6. 2% static pressure efficiency improved by 5. 72% and A-weighted sound level decreased by 3. 6 dB. Both prototype and modified fans exhibited approximately figure-8 shaped noise directivity. Noise reduction varied with perforation diameter. Superior noise reduction was observed in the fan inlet and outlet directions while lesser reduction occurred radially. Conclusion Perforations near the trailing edge can improve fan performance and reduce noise. However larger perforation diameters do not necessarily yield better results only appropriately sized perforations can enhance fan performance and reduce noise.