Fluorescence imaging is very useful for skin cancer lesions detection because of its properties of noninvasion and fast imaging. However, conventional fluorescence imaging devices' excitation light source and camera are usually separated, which will cause problems such as complicated structure, large volume, and poor illumination homogeneity. In this paper, we introduce a miniature portable fluorescence imaging device to diagnose skin cancer. A coaxial design has been introduced to combine the exciting light source and fluorescence receiver as an integral part, which significantly reduces the size of the device and ensures illumination homogeneity. The volume of the device is less than 3.5 × 3.5 × 9.5 cm³ with weight of 150 g, and the total power (including the excitation lamp) is only 1.5 W. It is used to detect the squamous cell carcinoma mice for demonstration. The results show that the location of the cancer lesions can be easily distinguished from the images captured by the device. It can be efficiently used to detect early skin tumors with noninvasion. It also has prospects to be integrated with other diagnostic methods such as ultrasound probe, for multiple diagnose of skin tumors thanks to its miniature size.