Alexodiy,
<!DOCTYPE html>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<style type="text/css">
</style>
<script>
window.addEventListener('DOMContentLoaded', function() {
var select = document.querySelector('#main'),
hide = document.querySelectorAll('[type="checkbox"]');
function change()
{
[].forEach.call(hide, function(el) {
el.removeAttribute('disabled');
el.checked = false;
if(select.value == 'one') {
el.checked = true;
el.setAttribute('disabled', 'disabled');
}
});
}
select.addEventListener('change', change);
change()
});
</script>
</head>
<body>
<select id="main" name="main" class="main_field" aria-required="true">
<option value="one">
Отметить все
</option>
<option value="two">
Выбрать несколько
</option>
</select>
<hr>
<label><input type="checkbox"/> описание 1</label>
<br>
<label><input type="checkbox" checked disabled /> описание 2</label>
<br>
<label><input type="checkbox" /> описание 3</label>
<br>
<label><input type="checkbox" /> описание 4</label>
</body>
</html>