Matching clearance is one of the key parameters to determine the accuracy and reliability of spherical inertia element. It is difficult to accurately measure the radius of the spherical inertia element due to the clearance and rough surface, which further lead to hardly control the matching clearance of ball bowl and ball. A laser differential confocal (LDC)based highprecision measurement method for spherical inertial element matching clearance is proposed in this work. Firstly, the antiscattering laser differential confocal radius measurement method is used to measure the radius of the bowl and the spherical crown, respectively. Then, the differential confocal radius measurement systems are utilized to measure the radius difference between the bowl and the crown. Finally, the matching clearance of the spherical inertia sphere is controlled by using the radius difference. Theoretical analysis and experimental results show that the method can measure the relative expansion uncertainty of matching clearance of the spherical crown and the ball bowl with the precision better than 20×10-6. It provides a new technology for the highprecision measurement and control of the spherical inertia element matching clearance.