High birefringence polarization-maintaining fibre is selected as the delay coils for YOFC current transformer. The whole winding process is controlled by low tension and special solidified adhesive to ensures the overall polarization-maintaining performance of the delay coil. The full-temperature crosstalk has less fluctuation, and it has excellent temperature characteristics and environmental stability. It can be used in optical fibre current sensor and other fields. The size of this series of delay coils can be customized according to the special needs of customers.