A multi-parameter dual-core fiber sensor is proposed to realize highly sensitive detection of illumination, temperature, and humidity, separately. Through partial grating etching of a one-side core, the interaction between the core and the external environment is enhanced. Then, combining the Mach-Zehnder effect of the dual core, a higher sensing sensitivity is obtained. Experimental results show the temperature sensitivity is higher than 6.1952 nm/°C. Besides, the humidity and illumination resolution can reach as accurate as 0.041 relative humidity (RH) and 0.025 light units, respectively. To have better multi-parameter sensing and demodulation, the deep learning algorithm of a one-dimensional convolutional neural network (1D-CNN) is used to reach an accuracy of 99.05% with ∼2.00 root mean square error (RMSE). We envision such an excellent multi-parameter sensor can be promising in environmental monitoring and intelligent manufacturing.