driver = webdriver.Firefox()
driver.get('http://www.stackoverflow.com')
header = driver.find_element_by_id('header')
all_children_by_css = header.find_elements_by_css_selector('*')
all_children_by_xpath = header.find_elements_by_xpath('.//*')
print('len(all_children_by_css): ' + str(len(all_children_by_css)))
print('len(all_children_by_xpath): ' + str(len(all_children_by_xpath)))
Selenium Python get all children elements