The present application relates to a synthesis method for N-methyl-3-substituted methyl-4-pyrazolamide derivative and N-methyl-3-substituted methyl-4-pyrazolic acid, including the following steps: step S1: synthesis of intermediate E; step S2: synthesis of intermediate D; step S3: synthesis of intermediate C; step S4: synthesis of N-methyl-3-substituted methyl-4-pyrazolamide derivative; and synthesis of N-methyl-3-substituted methyl-4-pyrazolic acid by decomposition of N-methyl-3-substituted methyl-4-pyrazolamide derivative.