after repiar library, can't open photo app

Could you please add some background information? What happens, when you try to open Photos? Do you get an error message? If yes, what is the message? Is Photos crashing?

What has changed, before you could no longer could open Photos? Did you upgrade to a new system version? Which system version is installed on your Mac?

And where is your Photos Library stored? Is it in your Pictures folder or somewhere else? If your Photos Library is on an external drive, tell us please, the file system format of the drive. The more recent system versions cannot work with a library on a drive formatted ExFAT. The library needs to be on a volume formatted MacOS Extended (Journaled) or APFS. The drive must not be used for Time Machine backups, and it needs a wired connection. DO not even think about putting the Photos Library on a NAS:

See: Move your Photos library to save space on your Mac - Apple Support

So you can open Photos and just cannot open a certain photo, which has been taken on your iPhone?

A Mac with OS X10.11 El Capitan cannot open photos taken on an iPhone, if they have been taken in the space saving HEIC format. See: Using HEIF or HEVC media on Apple devices - Apple Support

If the system version on your Mac is still OS X10.11 El Capitan and not at least macOS 10.13 High Sierra, you should keep the Settings Camera > Formats on your iPhone set to "Most Compatible" and not "High Efficiency". Then new photos will be taken in a format that your Mac can handle. Repairing the library will not help, if Photos cannot handle the format of some items in your iCloud Photos Library. Incompatible items have to be removed and converted to a more compatible format.

After you repair a library, Photos will sync your complete library again with iCloud and only after all photos from your library have been compared to the items in iCloud, will it download new photos from iCloud. If your library is large, it may take a while, until you can see the new photos in your Mac's photos Library.

You wrote "but can't in photo app, seems photos crashing when sync from icloud."

Is there an error message and a crash report, when you try to open Photos? Is Photos opening a Photos window, or does not come up at all?