There are two common Mandarin prepositions that correspond to the English "towards" : 向 (xiàng) and 往 (wáng). As with most Mandarin prepositions, 向 (xiàng) and 往 (wáng) must be followed by a noun or a noun phrase which is the object of the preposition.

The difference between these two Mandarin propositions is that 向 (xiàng) can be to describe movement towards a person or location, but 往 (wáng) is only used for movement towards a location, never a person.

There is also another Mandarin preposition that describes movement towards a person or place - 朝 （cháo). This is more commonly used in writing than in conversation.
Examples Of Mandarin Prepositions

Here are a few examples wher 向 (xiàng) and 往 (wáng) can be used:

    你們可以向下去。
    你们可以向下去。
    Nǐmen kěyǐ xiàng xiàqù.

    你們可以往下去。
    你们可以往下去。
    Nǐmen kěyǐ wáng xiàqu.

    你們可以朝下去。
    你们可以朝下去。
    Nǐmen kěyǐ cháo xiàqu.

    You can go down there.

In the above example, since the movement is towards a place, we can any one of the three prepositions, with the provision that 朝 （cháo) would be used in a literary context.

When describing movement towards a person, either 向 (xiàng) or 朝 （cháo) can be used, with the provision that 朝 （cháo) is used in a literary context.

    他向女朋友告别。
    Tā xiàng nǚpéngyou gàobié.

    他朝女朋友告别。
    Tā cháo nǚpéngyou gàobié.

    He bid farewell to his girlfriend.