for i in operate: if i.isalpha(): order.append(arr[ord(i)-65]) if operate[operate.index(i)-1].isalpha() and operate[operate.index(i)+1].isalpha(): b = order.pop() a = order.pop() calculate += a[0]*a[1]*b[1] order.append([a[0], b[1]]) elif i==')'and len(order)>=2: b=order.pop() a=order.pop() calculate +=a[0]*a[1]*b[1] order.append([a[0],b[1]]) print(calculate) 方法一中做了一点小修改，应该就可以避免括号里有三个矩阵,先计算最后两个的情况