Flexible pressure sensors are one of the vital component units in the next generation of wearable electronics for monitoring human physiological signals. In order to improve the sensing properties of the sensors, we demonstrate flexible, tunably resistive pressure sensors based on elastic microstructured polydimethylsiloxane (PDMS) film via a simple, low-cost colloid self-assembly technology, which uses monodispersed polystyrene (PS) microspheres as monolayer and an ordered sacrificial template. The sensors exhibit high sensitivity of -15 kPa-1 under low pressure (<100 Pa), with fast response time (<100 ms), high stability over 1000 cycles of pressure loading/unloading, low-pressure detection limit of 4 Pa, and wide working pressure regime (<5 kPa) by optimizing the size of PS microspheres. Moreover, the multipixel arrays of the pressure sensor are fabricated to illustrate the sensing ability of space pressure distribution. The developed flexible pressure sensors are successfully used to detect human neck pulse, show great promise for monitoring human body motions, and have potential applications in wearable devices.