The production and application of manufactured sand (MS) provide an excellent opportunity for China’s concrete industry to move towards low-carbon development. However, the complex characteristics of MS lead to poor workability and difficulty in prediction of concrete. In order to study the influencing factors and variation laws of workability for MS concrete based on rheological properties, this paper explored from two aspects: the characteristics of MS and concrete mix proportion parameters. Two-dimensional and three-dimensional relationship models between rheological properties and workability were established, and the significance of factors affecting the workability of tuff MS concrete based on rheological analysis was analyzed by grey relational analysis method. The experimental results show that the dynamic yield stress and plastic viscosity are closely related to the workability of concrete. With the increase of powder content, MS replacement rate, and sand ratio, the dynamic yield stress decreases first and then increases. The correlation between MS characteristics and various rheological properties of concrete is in a strongly correlated range. By properly adjusting the levels of these factors, the optimal workability required for actual engineering can be achieved.