你差一点就把数据-月份改成了6.。。

null

var $countdown = $('.countdown');

if ($countdown.length) {
  $countdown.each(function() {
    var $this = $(this),
      endDate = $this.data(),
      until = new Date(
        endDate.year,
        endDate.month || 0,
        endDate.day || 1,
        endDate.hours || 0,
        endDate.minutes || 0,
        endDate.seconds || 0
      );

    $this.countdown({
      until: until,
      padZeroes: true,
      format: 'dHMS',
      labels: ['Years', 'Month', 'Weeks', 'Days', 'Hours', 'Minutes', 'Seconds'],
      labels1: ['Years', 'Month', 'Weeks', 'Days', 'Hours', 'Minutes', 'Seconds']
    });
  });
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://www.wurreka.com/ict/virtual-conference/architecture/assets/vendors/countdown/jquery.plugin.min.js"></script>
<script src="https://www.wurreka.com/ict/virtual-conference/architecture/assets/vendors/countdown/jquery.countdown.js"></script>


<div data-year="2020" data-month="6" data-day="2" data-hours="5" data-minutes="0" data-seconds="0" class="countdown"></div>

请考虑以下示例。

null

var $countdown = $('.countdown');

if ($countdown.length) {
  $countdown.each(function(i, el) {
    $(el).countdown({
      until: new Date($(el).data("until")),
      padZeroes: true,
      format: 'dHMS',
      labels: ['Years', 'Month', 'Weeks', 'Days', 'Hours', 'Minutes', 'Seconds'],
      labels1: ['Years', 'Month', 'Weeks', 'Days', 'Hours', 'Minutes', 'Seconds']
    });
  });
}

.countdown span {
  margin-right: 3px;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://www.wurreka.com/ict/virtual-conference/architecture/assets/vendors/countdown/jquery.plugin.min.js"></script>
<script src="https://www.wurreka.com/ict/virtual-conference/architecture/assets/vendors/countdown/jquery.countdown.js"></script>

<div data-until="2020-07-02T05:00:00" class="countdown"></div>