Abstract: Propositional forms are expressed by symbols, but can propositional forms be equated with symbolization of propositions? Traditional logic's answer to this question seems to be self-evident, but mathematical logic makes this question complicated. Since predicate logic of mathematical logic introduced non-logical constants, symbolization of propositions and propositional forms were relatively separated, so that proposition forms have not simply equated with symbolization of propositions.Symbolization of propositions can be achieved with the aid of logic constants, but pure propositional forms don't contain non-logical constants, and there are not genuine non-logical constants in pure formal deduction.