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Hypergolic ignition of H₂O₂ and MEA-NaBH₄ by off-center collision of their droplets was experimentally studied, focusing on the characteristics and mechanism of droplet mixing, droplet heating and evaporation, and gas-phase ignition. The whole collision ignition process was divided into five stages, which were compared, respectively, with that of head-on collision. Under the condition of a slightly off-center collision (for cases where <i>B</i> < 0.35), H₂O₂ droplets penetrate MEA-NaBH₄ droplets after the collision and coalesce with it, but the internal H₂O₂ drop inside the MEA-NaBH₄ droplet does not form a stable sphere. Instead, it rotates and expands inside the mixed droplet. With <i>B</i> increasing to 0.59, the droplets no longer coalesce after collision but separate away, forming satellite droplets. In such cases, multi-ignition mode is observed. When <i>B</i> increases to a certain extent, specifically, 0.85, a grazing collision is observed such that no mass transfer exists during the interaction of droplets, which leads to ignition failure. A theoretical model quantifying droplet swelling rate was established to calculate the volume change of the droplet. It was found that the swelling can be attributed to the flash boiling of superheated internal H₂O₂ fluid. Meanwhile, the ignition delay time was found to linearly decrease with <i>B</i> at various <i>We</i>s until the extent where the chemical reaction takes over control, leading to an almost constant time delay defined as RDT. Additionally, the regime of ignition modes corresponding to different droplet mixing features is summarized in the <i>We</i>-<i>B</i> parametric space.