Detected the cracks in porcelain insulator is a strategy to prevent failure. This study proposes a remote detect technique to inspect the cracks in on-line porcelain insulator based on laser-generation based imaging (LGBI) method. Two porcelain insulators samples A and B were designed. Samples A is a 10kv porcelain insulator work outdoors, it has five artificial notch-type defects in the cylindrical surface of porcelain insulator. Sample B is a 10kv porcelain insulator work indoor with aging cracks. All defects in two specimens were detected by laser ultrasonic visualizing inspector (LUVI). Images are quite convenient to confirm cracks morphology. The experiment proves that the cracks in porcelain insulator can be detected by LUVI system.