helpful to 和 heplful for 都有"有助于"的意思，但 helpful to 较常用于接sb，而 helpful for也可以接sb，但多用于接sth或doing sth，表示"对....有益"。

例： Swimming is helpful for bones that are porous and weak.
游泳有助于改善骨质疏松和骨骼脆弱。
This system has been experimented in practical business work, it is helpful for promoting working efficiency.
本系统已在实际业务工作中投入使用，有助于提高工作效率。
he assertiveness training is very helpful for improving one's social skill.
自信训练对提高社交技巧很有帮助。

helpful for sb 的情况(sb一般是第一/二/三人称的主格或宾格)：
1、I think it's helpful for me to learn English well.
我认为它有助于我把英语学得更好。
2、Don't throw it, it is helpful for us to repair the bike.
别扔了它，它对我们修自行车有帮助。
3、I hope the two wise scholars'ideas on learning can be helpful for you.
我希望，这两位智者的思想可以在学习上对你们有所帮助。

help to sb的指向性较强，强调帮助的对向性，“什么”对“什么人”是“有用的、有帮助的、有益处的”。
例：The following information may be helpful to readers.
下列信息可能对读者有用。
This is written about me on the diagonal recurrent neural network procedures, may be helpful to you.
这是我写的关于对角递归神经网络的程序，或许对你有所帮助。
But many believe that informal channels and conversations in the work place can be helpful to employers.
但许多人认为，在工作场所的非正式沟通渠道和交谈可能对雇主们有益。
The principles should be helpful to the designer of a new engine system.
这些原则要有助于新发动机系统的设计人。