A linkable LED lighting system designed with an on line free setting method for adjusting operating parameters of at least one LED security light is disclosed. The linkable LED lighting system comprises at least one LED security light working in conjunction with a mobile phone loaded with an APP (software application) for controlling and setting at least one lighting characteristic of the at least one LED security light including time length settings, light intensity settings, color temperature settings, detection range settings, or signal frequency range or signal format settings for screening, accepting, and processing said wireless instruction signal(s) characterized with the same signal frequency range or the same signal format.