他将有一系列会议要参加(a series of)

He'll have a series of conferences to attend.

地道！

He will atend a series of meetings.就是这意思

He'll have a series of conferences to attend
说起来只是句式整齐。。。。。。

agree with aaa155.
不过把will改成need to可能更好

He will atend a series of meetings.更简练些！

He will atend a series of meetings.更简练些！---同意！

但是，你有一个typo，应该是attend。