I have just tried to install a *.deb package on my openSUSE tumbleweed host. I knew that openSUSE prefer RPM, so I searched how to install deb on openSUSE. Most of the answers told me to use alien to convert the package into a rpm package and install it. However, when I was installing alien, I found that dpkg was also installed as a dependency. So I tried to install the package via dpkg -i directly, and the software works fine.
So my question is, is it a proper way to install *.deb in openSUSE using dpkg -i without converting by alien directly? Will it damage my os?
As you do not explain what software that package is and as we are not mind readers, we have no idea what that software can do to your system.
Also, it is of course always better to use a version of software on openSUSE that is packaged for openSUSE. Did you try to find if such a version exists? Again we, not knowing what you want to install, can not help you with this searching.
I tried to install netease cloud music (which is just an electron-like app) and deepin-wine (A community-driven wine build, package can be found at deepin-wine-ubuntu/2.1deepin-libwine_2.18-12_i386.deb at master · wszqkzqk/deepin-wine-ubuntu · GitHub), both of them just provide *.deb packages.
Hi and welcome to the Forum 
I would look for alternatives since deepin-wine uses flash which is eol and insecure…
What services are you wanting to connect to for music? There is for example Pithos for connecting to pandora, I do have tizonia packaged, but not enabled for spotify. Perhaps you can enlighten out Forum users to your requirements…
IMO the biggest drawback to installing using a different package manager is that the package manager for RPMs won’t know anything about the DEB apps… Each package manager uses a different database. This wouldn’t be the same for instance if you use zypper and RPM because they’re designed to use the same database, but you shouldn’t use even other RPM package managers like dnf and yum.
Of course, if you install apps using incompatible package managers,
You’re creating a problem of possible contention and conflicts.
And, any libraries and other dependencies are probably installed in a different location (practically all distros have at least slightly different directory structures) so those files become “lost” on your system and won’t easily update or be removed later.
TSU
I have found an alternative of deepin-wine which works well in my host, thanks for yr suggestion!
Thx for your explanation!