Abstract: The tenet of cognitive linguistics is Embodied Philosophy and the foundation of cognitive grammar is experience and cognition. Based on this, the paper studies the relationship between grammar and metaphor. Grammar is developed through metaphorical mapping based on experiential cognition. Grammar itself is metaphor. Conversely, grammar is used to map the real world through the way of metaphor. Grammatical metaphor in Systematic Function Grammar cannot justify the view that the different grammatical expressing of the same meaning is metaphor and it belongs to grammatical rhetoric virtually. All these aim at expounding experiential, symbolic and metaphorical qualities of English grammar. There is no distinctive difference between cognition of English grammar and other cognition activities and the processes are characterized with convergence.