model.params是pandas.Series.仅当条目名称是有效的python名称时，才可以作为属性访问.

model.params is is a pandas.Series. Accessing as attribute is only possible if the name of the entry is a valid python name.

在这种情况下，您需要用引号将该名称索引，即model.params["C[T.foo]"]

In this case you need to index with the name in quotes, i.e. model.params["C[T.foo]"]

请参阅 http://pandas.pydata.org/pandas-docs/dev/indexing.html