To investigate the adsorption mechanism of cement on emulsified asphalt and superplasticizer in cement-asphalt mortar (CA mortar), the retardation effects of superplasticizer and emulsified asphalt on cement hydration were analyzed by the result of hydration heat measured by microcalorimetry. The effects of the type and adding sequence of superplasticizer on the adsorption of cement-emulsified asphalt were studied. In addition, the in-situ observation of the adsorption between cement and emulsified asphalt under the function of superplasticizer was conducted by using the polarizing microscope. Results showed that both emulsified asphalt and superplasticizer could retard the cement hydration and evidently extend the induction, while the co-adding of superplasticizer and emulsified asphalt resulted in evident synergistic effect in respect of the induction's extension. Competitive relationship obviously existed between the adsorption of polycarboxylate superplasticizer and emulsified asphalt on cement. In the case of coexistence of superplasticizer and emulsified asphalt, the cement was adsorbed by the former in priority. When the superplasticizer was added after emulsified asphalt, the adsorbed emulsified asphalt particles could be substituted by superplasticizer.