To ensure energy security and greenhouse gas emission, the world has decided to look for more sustainable and renewable energy sources. Biogas production from agricultural biomass is a fast growing market in the world. Suitable energy crops include maize, clover grass, alfalfa, sorghum, sudangrass, miscanthus and many others. Management considerations of energy crops such as harvesting time and nitrogen (N) application considerably influenced the biomass yield, quality of crop along with bio-methane production. Therefore, field study was conducted to determine the impact of harvesting times (HT) and nitrogen rates on the biomass yield of maize and production of bio-methane from it. The variable NR and HT, had a substantial influence on morphological, and compositional traits and bio-methane production. The N application at 200 kg ha^-1 produced the taller plants, with maximum leaves, leaf area, biomass yield, protein contents, acid detergent fiber (ADF), neutral detergent fiber (NDF), and lignin contents. In addition to that higher nitrogen rate (200 kg ha^-1) produced higher methane production however, it remained the same with 150 kg N ha^-1. Harvesting at 65 DAS produced the maximum taller plants with maximum leaf area, biomass yield and had maximum ADF and NDF which negatively affected the specific methane yield. Moreover, harvesting at 65 DAS produced maximum methane yield (MP) due to higher biomass yield (BY). It is concluded that N application @ 150 kg ha^-1 and harvesting at 65 DAS can be suitable for getting the higher bio-methane production under semi-arid conditions of Pakistan.