Through the orthogonal test design,the modifier was prepared to modify ferrochrome slag.The orthogonal test is animportant method to study the multi factor test problems.The accuracy of the orthogonal test results is low by using range and variance analysis only,as well as the disadvantages of increasing the total number of tests or reducing the number of indepen-dent factors.Based on the decoupling method of mortar strength and regression analysis,the range and variance analysis of orthogonal test results were tested,and the influence of four factors of modifier（sodium silicate,cement,slag powder and soa-king time of ferrochrome slag） on the intermediate variable （water absorption of ferrochrome slag modified） was quantita-tively studied,and the influence of water to binder ratio on the strength was further analyzed during the preparation of mortar.The results showed that there was a coupling relationship between the preparation of modifier and the preparation of modified ferrochrome slag mortar,which was decoupled and quantitatively analyzed by SPSS software and other means.This study provided a way for data processing and statistics to use decoupling method to sort out the influence relationship,and combined with regression analysis to achieve a way from qualitative analysis to quantitative analysis.