Abstract: With continuous increase of the access volume and permeability of distributed power in the distribution network,the traditional current differential protection scheme may have sensitivity and selectivity problems. In this paper,the characteristics of current amplitude faults are analyzed mathematically from in-zone faults and out-zone faults respectively and it is concluded that the amplitude of current at both ends of the feeder will vary greatly under different faults,and at the same time,the braking coefficient will play a decisive role in selectivity and sensitivity of current differential protection. Next,a new protection scheme based on fault current amplitude ratio fitting with the braking coefficient is proposed.Finally,through theoretical analysis and MATLAB/Simulink simulation, we can see that compared with the traditional current differential protection scheme,the scheme improves the sensitivity on the premise of ensuring the selectivity,and has higher engineering practicability.