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<p>Energetic oxygen ions (1–40&thinsp;keV) observed by the Magnetospheric Multiscale (MMS) satellites at the duskside magnetopause boundary layer during phase 1 are investigated. There are 57 duskside magnetopause crossing events identified during intense substorms (<span class="inline-formula">AE&gt;500</span>&thinsp;nT). These 57 events of energetic <span class="inline-formula">O⁺</span> at the duskside magnetopause include 26 events during the expansion phase and 31 events during the recovery phase of intense substorms. It is found that the <span class="inline-formula">O⁺</span> density in the duskside magnetopause boundary layer during the recovery phase (0.081&thinsp;cm<span class="inline-formula">⁻³</span>) is larger than that during the expansion phase (0.069&thinsp;cm<span class="inline-formula">⁻³</span>). The 26 events of energetic <span class="inline-formula">O⁺</span> ions at the duskside magnetopause during intense substorm expansion phase are all under the southward interplanetary magnetic field (IMF). There are only seven events under northward IMF, and they all occurred during the intense substorm recovery phase. The density of energetic <span class="inline-formula">O⁺</span> at the duskside magnetopause ranges from 0.007 to 0.599&thinsp;cm<span class="inline-formula">⁻³</span>. The maximum density of <span class="inline-formula">O⁺</span> occurred during the intense substorm recovery phase and under southward IMF. When the IMF is southward, the <span class="inline-formula">O⁺</span> density shows an exponential increase with the IMF <span class="inline-formula"><i>B</i>_<i>z</i></span> absolute value. Meanwhile, the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M12" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msup><mi mathvariant="normal">O</mi><mo>+</mo></msup><mo>/</mo><msup><mi mathvariant="normal">H</mi><mo>+</mo></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="36pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="381c4c0cf06e56af75023ee66d0cebd1"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="angeo-38-123-2020-ie00001.svg" width="36pt" height="14pt" src="angeo-38-123-2020-ie00001.png"/></svg:svg></span></span> density ratio shows an exponential growth with the IMF <span class="inline-formula"><i>B</i>_<i>y</i></span>. These results agree with previous studies in the near-Earth magnetosphere during intense substorm. It is suggested that <span class="inline-formula">O⁺</span> abundance in the duskside magnetopause boundary layer has a close relation to <span class="inline-formula">O⁺</span> variations in the near-Earth magnetosphere during intense substorms.</p>