Sure, take a look at sys.version and sys.version_info.
For example, to check that you are running Python 3.x, use
import sys
if sys.version_info[0] < 3:
raise Exception("Must be using Python 3")
Here, sys.version_info[0] is the major version number. sys.version_info[1] would give you the minor version number.
In Python 2.7 and later, the components of sys.version_info can also be accessed by name, so the major version number is sys.version_info.major.
See also How can I check for Python version in a program that uses new language features?