物理学中，正则量子化是多种对古典理论进行量子化的数学方法中的一种；在对古典场论进行量子化时，又称二次量子化。「正则」这个词其实源自古典理论，指的是理论中一种特定的结构（称作辛结构（Symplectic structure）），这样的结构在量子理论中也被保留。这在保罗·狄拉克尝试建构量子场论时由他首先强调。

普通的量子力学方法只能处理粒子数守恒的系统。但在相对论量子力学中，粒子可以产生和湮没，普通量子力学的数学表述方法不再适用。二次量子化通过引入产生算符和湮没算符处理粒子的产生和湮没，是创建相对论量子力学和量子场论的必要数学手段。相比普通量子力学表述方式，二次量子化方法能够自然而简洁的处理全同粒子的对称性和反对称性，所以即使在粒子数守恒的非相对论多体问题中，也被广泛应用。

Second quantization is a formalism used to describe and analyze quantum many-body systems. It is also known as canonical quantization in quantum field theory, in which the fields (typically as the wave functions of matters) are thought of as field operators, in a similar manner to how the physical quantities (position, momentum etc.) are thought of as operators in first quantization. The key ideas of this method were introduced in 1927 by Dirac, and were developed, most notably, by Fock and Jordan later.