In order to establish a more advanced dopamine biosensor based on the carboxylated graphene/cysteamine modified gold electrode for quantitative detection of catecholamine neurotransmitter dopamine, cysteamine was modified on gold electrode by self-assembly technology, and then the carboxylated graphene was fixed on the modified electrode by 1-ethyl-\[3-dimethylaminopropyl\] carbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS) crosslinker to prepare the dopamine electrochemical sensor. Firstly, the modified electrode was characterized to test its sensitivity, and then the electrochemical behavior of the electrode in dopamine solution was studied by cyclic voltammetry, including optimization of detection conditions and determination of sensor performance. Characterization results of the modified electrode showed that the carboxylated graphene/cysteamine modified gold electrode improved the electron transfer ability of the electrode and had higher sensitivity. Through single factor experiments, the best detection condition was to use 0.30 mol·L-1 phosphate buffer solution (PBS) with pH 6.00 to prepare dopamine solution, and the scanning rate  set as 200 mV·s-1. Under the optimal detection conditions, the magnitude of the current of the prepared dopamine electrochemical sensor increased with the increase of dopamine concentration, showing a good linear relationship in the range of 1.0×10-3 ~ 3.5×10-3 mol·L-1. The linear regression equation was I=8.120 6C+7.017, and the correlation coefficient R2 was 0.999 5. Moreover, the sensor had good precision, strong stability and certain anti-interference capability. The research results provided support for the determination of dopamine content in drug dopamine hydrochloride injection.