We demonstrate a $12\mathrm{km}$ differential pulse-width pair Brillouin optical time-domain analysis (DPP- BOTDA) using $40\mathrm{ns}$ and $50\mathrm{ns}$ pulses with DC-coupled detection. A spatial resolution of $1\mathrm{m}$ and a narrowband Brillouin gain spectrum of $33\mathrm{MHz}$ are obtained simultaneously compared with $88\mathrm{MHz}$ with the use of $10\mathrm{ns}$ pulses in a conventional BOTDA. The experimental results show that the differential Brillouin gain of a $40/50\mathrm{ns}$ pulse pair is 7 times stronger than the direct Brillouin gain of BOTDA with the use of a $10\mathrm{ns}$ pulse, and the temperature uncertainty is $0.25°\mathrm{C}$ compared with $1.8°\mathrm{C}$ for a $10\mathrm{ns}$ pulse. As the pulse-width difference decreases from $10\mathrm{ns}$ to $1\mathrm{ns}$ , corresponding to a spatial resolution from $1\mathrm{m}$ to $10\mathrm{cm}$ , the prediction of temperature uncertainty will only increase from $0.25°\mathrm{C}$ to $0.8°\mathrm{C}$ for DPP-BOTDA over a $12\mathrm{km}$ long single-mode fiber.