import pandas as pd df1 = pd.DataFrame({'A': [1, 2, 3]}) df2 = df1 # df2 引用 df1 的同一块内存 def modify1(df2): df2['A'][0] = 99 # 修改 df2 def modify2(df2): df2= df2[df2['A'][0]==99] # 修改 df2 modify1(df2) modify2(df2) print(df1)