您可以使用. slideToggle()

$(document).on('click', '#open', function () {
        $('#collapseOne').slideToggle()
    })

#collapseOne { display:none }

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/2.2.2/jquery.min.js"></script>
I'm working on accordion, And Opening a panel on click on another link <div id="open">Open It</div>. but It's not opening smoothly. However when I open by click on card header it's opening very smoothly. How to achieve this?

html

<div id="accordion">
  <div class="card">
    <div class="card-header" id="headingOne">
      <h5 class="mb-0">
        <button class="btn btn-link" data-toggle="collapse" data-target="#collapseOne" aria-expanded="true" aria-controls="collapseOne">
          Collapsible Group Item #1
        </button>
      </h5>
    </div>

    <div id="collapseOne" class="collapse" aria-labelledby="headingOne" data-parent="#accordion">
      <div class="card-body">
        Anim pariatur cliche reprehenderit, enim eiusmod high life accusamus terry richardson ad squid. 3 wolf moon officia aute, non cupidatat skateboard dolor brunch. Food truck quinoa nesciunt laborum eiusmod. Brunch 3 wolf moon tempor, sunt aliqua put a bird on it squid single-origin coffee nulla assumenda shoreditch et. Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt sapiente ea proident. Ad vegan excepteur butcher vice lomo. Leggings occaecat craft beer farm-to-table, raw denim aesthetic synth nesciunt you probably haven't heard of them accusamus labore sustainable VHS.
      </div>
    </div>
  </div>
  
    <div id="open">Open It</div>
</div>

从你的类/数据来看-看起来你在使用bootstrap 4 accordion。
在使用bootstrap等库时，谨慎的做法是使用所提供的API，在本例中：

$(document).on('click', '#open', function () {
    $('#collapseOne').collapse('toggle')
})

如果您只想显示而不想切换，还有其他选项，如.collapse("show")。
更新了 Bootstrap ：
x一个一个一个一个x一个一个二个x