The present invention relates to a method of preparing a conjugated diene-based polymer by continuous polymerization using two or more reactors, and relates to a method of preparing a conjugated diene-based polymer which is capable of providing a conjugated diene-based polymer having improved Mooney viscosity and excellent cis 1,4 bond content and linearity, by controlling the injection amount of a conjugated diene-based monomer to each reactor in a specific ratio and resolving the deterioration phenomenon of physical properties, which might be generated in continuous reaction.