Multi-cylinder aquaculture constant temperature system capable of respectively controlling cold and warm temperatures

The invention relates to the technical field of constant-temperature aquaculture, in particular to a multi-cylinder aquaculture constant-temperature system capable of respectively controlling cold and warm temperatures, which comprises a variable-frequency compressor, a plurality of fixed-frequency compressors, a first condenser, a second condenser, a gas-liquid separator, an oil separator and a pair of liquid storage devices, and the variable-frequency compressor is communicated with the plurality of fixed-frequency compressors in parallel through parallel compressor oil balancing pipes. Through the parallel connection technology of the variable-frequency compressor and the fixed-frequency compressor, when the constant-temperature load of the fish tank is increased till the constant-temperature requirement cannot be met when the variable-frequency compressor operates at full load, the fixed-frequency compressor connected with the fish tank in parallel is started step by step, and the parallel connection desi