There isn't one, really. At least, to nowhere near the same extent as there is in the US. We have a libertarian party, but they're a tiny party in the grand political scheme of things; even more so than in the US. We don't have a two-party system, we've got about 8-9 major political parties, but our LP is not in that group. They've never gotten enough votes to hold a single seat in parliament, or any local government positions as far as I'm aware, but their membership has grown massively in recent years (of course, this growth is relative; the same absolute growth would barely be noteworthy for one of the bigger parties).

We have bigger parties that have some pro-liberty positions, but they all come with plenty of other positions that would be considered anti-liberty. Of the main parties (the ones that actually have a chance of being in government), the one I find the least objectionable is called D66 (note that I said 'least objectionable', not 'best'). I wouldn't describe them as libertarian, but I would describe them as socially liberal and economically conservative, which is as good as it's going to get from the major parties.