class SpiderCharacteristicType(models.Model):
    name = models.CharField(_(u'Name'), max_length=255)
class SpiderCharacteristic(models.Model):
    characteristic_type = models.ForeignKey(SpiderCharacteristicType)
    value = models.CharField(_(u'Value'), max_length=255)
    item = models.ForeignKey(SpiderItem)
    
class SpiderItem(models.Model):
    article = models.CharField(_(u'Артикул'), max_length=255, help_text=u'')
    name = models.CharField(_(u'Наименование'), max_length=255, help_text=u'')
   

mydict = {'article__exact': self.article,
          'vendor_id__exact': self.vendor_id,
            }
            
self.features = {}
if item[u'Цвет'] != '':
   self.features['color'] = item[u'Цвет']
if item[u'Размер'] != '':
   self.features['size'] = item[u'Размер']
mydict['spidercharacteristic__value'] = self.features.values()
try:
   self.obj = SpiderItem.objects.get(**mydict)
except ObjectDoesNotExist:    
   print 'error'

mydict['spidercharacteristic__value'] = self.features.values()

for self.dict_key, self.dict_value in self.features.items():
   mydict['spidercharacteristic__characteristic_type']=SpiderCharacteristicType.objects.get(name=self.dict_key)
   mydict['spidercharacteristic__value'] = self.dict_value

SpiderItem.objects.filter(
  article__exact = self.article, 
  vendor_id__exact =self.vendor_id, 
  Q(spidercharacteristic__characteristic_type='color', 
  spidercharacteristic__value='red') | 
  Q(spidercharacteristic__characteristic_type='size', 
  spidercharacteristic__value='s'))

for self.dict_key, self.dict_value in self.features.items():

SpiderItem.objects.get(article='7261', Q(spidercharacteristic__characteristic_type=SpiderCharacteristicType.objects.get(name='size'),
  spidercharacteristic__value='S') , Q(spidercharacteristic__characteristic_type=SpiderCharacteristicType.objects.get(name='color'), 
  spidercharacteristic__value=u'сиреневый'))
...         
  File "<console>", line 1
SyntaxError: non-keyword arg after keyword arg

>>> SpiderCharacteristic.objects.filter(item=SpiderItem.objects.get(article='14773'))
[<SpiderCharacteristic: color - сиреневый>, <SpiderCharacteristic: size - S>]
>>> SpiderItem.objects.filter(Q(spidercharacteristic__characteristic_type=SpiderCharacteristicType.objects.get(name='size'), spidercharacteristic__value='S') & Q(spidercharacteristic__characteristic_type=SpiderCharacteristicType.objects.get(name='color'), spidercharacteristic__value=u'сиреневый'))
...         
[]

SpiderItem.objects.filter(
  article__exact = self.article, 
  vendor_id__exact =self.vendor_id, 
  Q(spidercharacteristic__characteristic_type='color', 
  spidercharacteristic__value='red') &
  Q(spidercharacteristic__characteristic_type='size', 
  spidercharacteristic__value='s'))