Microtremor survey is a kind of passive-source methods which uses ambient ground tremors for geological investigation. Compared with traditional geophysical methods, it is more flexible, cost-efficient, and environmentally friendly. Most currently used geophones are expensive and bulky, and therefore inconvenient to large-scale deployment. In this study, a no-cable low-cost geophone was optimized to suit for large-scale microtremor survey. The method of optimization is based on the following four points: First, it selects a sensor through the analysis of the self-noise of to meet the needs of microtremor survey. Second, it chooses the right operational amplifier and AD conversion module. Third, it integrates design of the entire system without using external module. And fourth, it makes a low-cost design of the geophone system, including selection of low-cost hardware components and reducing the amount of software code. Finally, the optimized geophone was used in three areas with different geological conditions in order to verify the rationality of the improvement and the possibilities for large-scale microtremor survey. The purpose of optimization has been achieved in this research. The no-cable geophone wrights only 600 g, and the maximum average power cost does not exceed 0. 1 mW. The entire system costs less than 2000 RMB. The most important thing is the optimized geophone can record the microtremor signal from O. 5 to 20 Hz effectively. Experiments show that in different geological conditions the geophone can be setup quickly and work smoothly and reliably. The results of microtremor survey experiments are consistent with the existing geological data. Because the new geophone is much cheaper than the existing microtremor survey equipment, it is possible to use it in low-cost large-scale survey. The optimized geophone has a very small volume and light weight, and can be rapidly emplacedinto a variety of detector arrays. After the emplacement of large number of geophones, it can easily and quickly conduct survey to two-dimensional or three-dimensional velocity structure of the area. Such microtremor survey with environment-friendly and low-cost advantages has broad application prospects.