我认为您需要total_seconds：
print (df['col'].dt.total_seconds())
样品：
df = pd.DataFrame({'date1':pd.date_range('2015-01-01', periods=3),
'date2':pd.date_range('2015-01-01 02:00:00', periods=3, freq='23H')})
print (df)
date1 date2
0 2015-01-01 2015-01-01 02:00:00
1 2015-01-02 2015-01-02 01:00:00
2 2015-01-03 2015-01-03 00:00:00
df['diff'] = df['date2'] - df['date1']
df['seconds'] = df['diff'].dt.total_seconds()
print (df)
date1 date2 diff seconds
0 2015-01-01 2015-01-01 02:00:00 02:00:00 7200.0
1 2015-01-02 2015-01-02 01:00:00 01:00:00 3600.0
2 2015-01-03 2015-01-03 00:00:00 00:00:00 0.0
df['diff'] = df['date2'] - df['date1']
df['diff'] = df['diff'].dt.total_seconds()
print (df)
date1 date2 diff
0 2015-01-01 2015-01-01 02:00:00 7200.0
1 2015-01-02 2015-01-02 01:00:00 3600.0
2 2015-01-03 2015-01-03 00:00:00 0.0
如果需要转换为int：
df['diff'] = df['date2'] - df['date1']
df['diff'] = df['diff'].dt.total_seconds().astype(int)
print (df)
date1 date2 diff
0 2015-01-01 2015-01-01 02:00:00 7200
1 2015-01-02 2015-01-02 01:00:00 3600
2 2015-01-03 2015-01-03 00:00:00 0
602392714
清零编程群