转换为unix\u timestamp，sum，除以3，转换为bigint并转换回hh:mm:ss：

with data as --Data example. Use your table instead
(select '12:10:30' start_time,'01:10:00' end_time, '02:10:00' duration)

select from_unixtime(cast((unix_timestamp(start_time,'HH:mm:ss')+ unix_timestamp(end_time,'HH:mm:ss')+unix_timestamp(duration,'HH:mm:ss'))/3 as bigint),'HH:mm:ss') from data;

结果：

05:10:10

请参见此处的测试：http://demo.gethue.com/hue/editor?editor=285484&type=hive
对于单列：
转换为unix timestamp，以秒为单位计算平均值，转换为bigint（平均值是double，会有部分秒精度损失），最后将其转换回字符串时间格式：

with data as --Data example. Use your table instead
(select stack(2,'12:10:30','01:10:00') as timeStr)

select from_unixtime(cast(avg(unix_timestamp(timeStr,'HH:mm:ss'))as bigint),'HH:mm:ss') from data;

结果：

06:40:15

请参见此处的测试：http://demo.gethue.com/hue/editor?editor=285464&type=hive