Abstract: For problem that weighing method cannot realize real-time and on-line detection for metal dust concentration, basic principle of light scattering method and charge induction method for metal dust concentration detection were analyzed, and signal acquisition and processing circuits for metal dust concentration detection were designed which were respectively based on light scattering method and charge induction method. The experimental results show that errors of light scattering method and charge induction method are small in early detection. Error of light scattering method increases and detection value is higher than standard reference value after long-time continuous detection, while detection accuracy of charge induction method is still high.