The invention discloses a method for synthesizing 3,3-dimethyl-4-pentenoic acid methyl ester, which comprises the following steps of: I) at the temperature of between 0 and 40 DEG C, uniformly mixing trimethyl orthoacetate, a catalyst and isoamyl enol in a molar ratio of 1:(0.0005-0.02):(0.1-0.5) in a reactor by stirring, and reacting for 0.2 to 2 hours to generate synthetic feed liquid of the 3,3-dimethyl-4-pentenoic acid methyl ester; and II) removing a byproduct of methanol and the excessive trimethyl orthoacetate from the synthetic feed liquid of the 3,3-dimethyl-4-pentenoic acid methyl ester obtained in the step I), rectifying the remaining materials to obtain a 3,3-dimethyl-4-pentenoic acid methyl ester product. The method for synthesizing the 3,3-dimethyl-4-pentenoic acid methyl ester has high reaction speed, short cycle, less byproduct of tar, high reaction yield of over 88 percent, high product content of over 99.5 percent and concise process, and is suitable for industrial production.