In this paper, a model free uncalibrated visual servoing algorithm based on recursive least squares is proposed and discussed in depth. No robot kinetics or dynamics, camera calibration or target model to be tracked would be ever needed. Based on the brief retrospection of RLS filter as well as its theoretical analysis, i.e. Wiener-Hopf condition, the core uncalibrated visual servoing algorithm based on recursive least squares is explored in detail. The experimental results of both static and moving targets applied on a Puma-560 6DOFs industrial robot simulation verifies its performances.